{"id":18805,"date":"2026-01-02T20:52:16","date_gmt":"2026-01-02T20:52:16","guid":{"rendered":"https:\/\/www.comet.com\/site\/?page_id=18805"},"modified":"2026-09-03T16:39:59","modified_gmt":"2026-09-03T16:39:59","slug":"phoenix-vs-opik","status":"publish","type":"page","link":"https:\/\/www.comet.com\/site\/products\/opik\/compare\/phoenix-vs-opik\/","title":{"rendered":"Phoenix vs. Opik"},"content":{"rendered":"\n<div class=\"wp-block-group alignwide is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-group alignwide is-layout-constrained wp-block-group-is-layout-constrained\" style=\"margin-top:var(--wp--preset--spacing--100);margin-bottom:var(--wp--preset--spacing--50)\">\n<h1 class=\"wp-block-heading has-text-align-left alignwide\" style=\"margin-top:var(--wp--preset--spacing--50);margin-bottom:var(--wp--preset--spacing--50)\"><strong><strong>Arize Phoenix vs. Opik: Open-Source AI Agent Observability and LLM Evaluation in 2026<\/strong><\/strong><\/h1>\n\n\n\n<p class=\"alignwide wp-block-paragraph\"><em>Last updated: 2026-08-31<\/em><\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-large is-resized\" style=\"margin-top:var(--wp--preset--spacing--100);margin-bottom:var(--wp--preset--spacing--100)\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"193\" src=\"https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/12\/phoenix-vs-opik-1024x193.png\" alt=\"Comparison of Phoenix and Opik for LLM evaluation\" class=\"wp-image-18811\" style=\"width:562px;height:auto\" srcset=\"https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/12\/phoenix-vs-opik-1024x193.png 1024w, https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/12\/phoenix-vs-opik-300x56.png 300w, https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/12\/phoenix-vs-opik-768x144.png 768w, https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/12\/phoenix-vs-opik-1536x289.png 1536w, https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/12\/phoenix-vs-opik-2048x385.png 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<div class=\"wp-block-group has-border-color has-custom-decorative-border-dark-border-color has-tertiary-background-color has-background is-layout-constrained wp-block-group-is-layout-constrained\" style=\"border-width:1px;border-top-left-radius:8px;border-top-right-radius:8px;border-bottom-left-radius:8px;border-bottom-right-radius:8px;margin-top:var(--wp--preset--spacing--100);margin-bottom:var(--wp--preset--spacing--100);background-image:var(--wp--preset--gradient--custom-dark-background);\">\n<div class=\"wp-block-group is-nowrap is-layout-flex wp-container-core-group-is-layout-9b541e26 wp-block-group-is-layout-flex\" style=\"border-left-color:var(--wp--preset--color--background);border-left-width:3px;padding-left:var(--wp--preset--spacing--24)\">\n<p class=\"alignwide has-background-color has-text-color has-link-color has-body-m-font-size wp-elements-1 wp-block-paragraph\">\u2728 <strong>The short answer<\/strong>: Choose Opik if you want the more permissive Apache-2.0 license, native Test Suites, production evaluation and alerts in the open-source product, broader multimodal workflows, and optimization that extends beyond prompts to tools and agents. Choose Arize Phoenix if OpenTelemetry and OpenInference are at the center of your stack, you need OTLP over gRPC, rely heavily on embedding and retrieval analysis, or expect to move into Arize AX for managed infrastructure across GenAI and predictive ML \u2014 though Comet\u2019s ML Experiment Management platform is worth comparing to Arize for this as well.<\/p>\n<\/div>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">Both platforms trace, evaluate, and help debug LLM and agent applications. Both can be deployed on your infrastructure, and neither limits its self-hosted product to basic tracing.<br><br>The practical difference is how each platform connects the workflows around those traces. Opik is an open-source LLM observability and evaluation platform built by Comet. Opik packages observability, online evaluation, alerts, regression Test Suites, prompt and tool optimization, and AI-assisted debugging into one platform. Phoenix takes a standards-first approach built around OpenTelemetry and OpenInference, with flexible evaluation libraries, experiments, prompt management, and direct integration with existing test runners.<br><br>Phoenix can run in production. The distinction is operational: Phoenix users deploy, scale, and support the infrastructure themselves, while Arize positions its separate commercial product, Arize AX, as the managed option for auto-scaling, enterprise support, production alerting, custom dashboards, and large evaluation workloads. Opik includes production monitoring, online evaluation, and alerts in its full open-source product.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group alignfull has-custom-alt-background-dark-background-color has-background is-layout-constrained wp-container-core-group-is-layout-e5a791a7 wp-block-group-is-layout-constrained\" style=\"border-top-color:var(--wp--preset--color--custom-decorative-border-dark);border-top-width:1px;border-bottom-color:var(--wp--preset--color--custom-decorative-border-dark);border-bottom-width:1px;margin-top:var(--wp--preset--spacing--100);margin-bottom:var(--wp--preset--spacing--100);padding-top:var(--wp--preset--spacing--100);padding-bottom:var(--wp--preset--spacing--100)\">\n<div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-left has-display-s-font-size\"><strong>What are the best alternatives to Arize Phoenix in 2026?<\/strong><\/h2>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\">The four platforms teams most often evaluate alongside Arize Phoenix are:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Opik:<\/strong> An Apache-2.0 platform for agent observability, evaluation, testing, and optimization, with a free full-feature self-hosted deployment.<\/li>\n\n\n\n<li><strong>Langfuse:<\/strong> An open-source platform focused on LLM tracing, prompt management, evaluation, and application analytics.<\/li>\n\n\n\n<li><strong>LangSmith:<\/strong> LangChain\u2019s proprietary observability and evaluation platform, with its deepest integration into LangChain and LangGraph.<\/li>\n\n\n\n<li><strong>Weights &amp; Biases Weave:<\/strong> Evaluation and observability tooling designed to work within the broader W&amp;B ecosystem.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">For teams that require a full platform inside their own infrastructure, Opik and Phoenix are the most direct comparison. Both support free self-hosting, broad framework coverage, datasets, experiments, tracing, and evaluations. The bigger differences are licensing, OpenTelemetry architecture, testing workflows, production monitoring, and how much work happens inside the product rather than in external infrastructure or testing tools.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-left has-display-s-font-size\"><strong>What is the difference between Arize Phoenix and Opik?<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The simplest distinction is that <strong>Phoenix is standards-first, while Opik is workflow-first<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Phoenix is built around OpenTelemetry and the OpenInference semantic conventions maintained by Arize. It accepts OTLP over HTTP and gRPC and provides instrumentation for popular model providers, frameworks, and programming languages. This makes Phoenix particularly attractive to teams that already operate OpenTelemetry collectors and want AI traces to fit into an existing observability architecture.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Opik also accepts OpenTelemetry data and can receive traces from any language with an OpenTelemetry SDK, although its current direct OpenTelemetry integration supports HTTP transport rather than gRPC. Opik\u2019s emphasis is on what developers do after instrumentation: inspect a trace, turn a failure into a test, run regression suites, monitor the corresponding behavior in production, and optimize the prompts, model parameters, or tools involved.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">There is also a meaningful licensing difference. Opik uses Apache License 2.0. Phoenix uses Elastic License 2.0, which allows teams to inspect, modify, distribute, and self-host Phoenix but prohibits offering a substantial set of Phoenix functionality to third parties as a hosted or managed service.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-left has-display-s-font-size\"><strong>How do Arize Phoenix and Opik compare, feature by feature?<\/strong><\/h2>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\">They match on the core observability and evaluation jobs. Both support traces and spans, datasets, experiments, deterministic evaluators, LLM-as-a-judge, human feedback, production trace analysis, session-level evaluation, prompt management, and AI-assisted investigation.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">They diverge more clearly in five areas:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Opik turns regression testing into a native platform workflow.<\/strong><\/li>\n\n\n\n<li><strong>Phoenix offers the deeper OpenTelemetry and OpenInference architecture.<\/strong><\/li>\n\n\n\n<li><strong>Opik includes production evaluation and alerts in its open-source product, while Phoenix directs continuous alerting and stakeholder dashboards to Arize AX.<\/strong><\/li>\n\n\n\n<li><strong>Opik\u2019s optimization covers prompts, model parameters, tools, MCP workflows, and multimodal agents.<\/strong><\/li>\n\n\n\n<li><strong>Phoenix has stronger first-party embedding visualization and a clearer migration path into Arize\u2019s predictive-ML observability stack<\/strong>.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group alignfull is-layout-flow wp-block-group-is-layout-flow\">\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<h2 class=\"wp-block-heading has-text-align-left\"><strong>Opik vs. Arize Phoenix Feature Comparison<\/strong><\/h2>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\">The following rows reflect each vendor\u2019s public documentation as of August 31, 2026. Where a capability is not clearly documented, the table says so rather than treating missing documentation as proof that the feature does not exist.<\/p>\n<\/div>\n\n\n\n<figure class=\"wp-block-table alignwide feature-table is-style-stripes unstyled-links\"><table class=\"has-background-color has-text-color has-link-color has-fixed-layout\" style=\"border-style:none;border-width:0px\"><thead><tr><th class=\"has-text-align-left\" data-align=\"left\">Feature<\/th><th class=\"has-text-align-left\" data-align=\"left\">Opik (by Comet)<\/th><th class=\"has-text-align-left\" data-align=\"left\"><strong>Arize Phoenix<\/strong><\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-left\" data-align=\"left\">License<\/td><td class=\"has-text-align-left\" data-align=\"left\">Open source, Apache-2.0<\/td><td class=\"has-text-align-left\" data-align=\"left\">Elastic License 2.0. Free to self-host, but the license restricts offering substantial Phoenix functionality as a hosted or managed service.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Free self-hosting<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\"><strong>Yes. Full AI observability and agent-testing feature set; same core codebase as the hosted versions.<\/strong><\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\"><strong>Yes. Phoenix has no separate paywalled edition or gated Phoenix feature set.<\/strong><\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Managed cloud<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Opik Cloud, with Free, Pro, and Enterprise plans.<\/td><td class=\"has-text-align-left\" data-align=\"left\">Phoenix itself is self-hosted. Arize AX is the separate managed commercial platform.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Tracing (traces and spans)<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes, including model calls, retrieval, tool calls, agent execution graphs, sessions, cost, and feedback.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes, including model calls, retrieval, tool use, custom logic, sessions, and OpenInference span kinds.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">OpenTelemetry<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Native OpenTelemetry ingestion from SDKs across many languages; HTTP transport currently supported.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">OpenTelemetry and OpenInference are foundational to the platform; OTLP over HTTP and gRPC is supported.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Offline evaluation on datasets<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes, through datasets, experiments, built-in metrics, custom metrics, and Test Suites.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes, through datasets, experiments, client-side SDK evaluators, and server-side UI evaluators.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Production-trace evaluation<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Online Evaluation rules score traces, spans, or conversations as production data arrives.<\/td><td class=\"has-text-align-left\" data-align=\"left\">Evaluators can run on production traces; Phoenix directs continuous alerting and threshold-triggered monitoring to Arize AX.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Native regression Test Suites<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Test Suites are first-class UI and SDK objects with test items, natural-language assertions, execution policies, repeated runs, and pass thresholds.<\/td><td class=\"has-text-align-left\" data-align=\"left\">Phoenix maps ordinary pytest suites to datasets and experiment runs. The testing workflow is strong, but it is centered on an external test runner rather than a dedicated in-product Test Suite object.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">CI quality gates<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Test Suites and experiments can be incorporated into CI workflows.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. The Phoenix pytest plugin uses normal test assertions and exit codes to fail CI when a hard invariant breaks.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Deterministic evaluators<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes, including exact match, contains, regular expressions, JSON checks, edit distance, and custom code metrics.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes, including exact match, regular expressions, custom heuristics, and custom evaluators.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">LLM-as-a-judge<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes, with built-in metrics for hallucination, relevance, moderation, retrieval quality, task completion, tool correctness, conversations, and more.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes, with configurable judge models, structured scoring, explanations, prebuilt templates, and custom rubrics.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Human review and annotation<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Annotation queues support trace-level and conversation-level review.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Phoenix supports annotations, labels, user feedback, and human review of traces and experiments.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Session and conversation evaluation<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Opik can evaluate complete multi-turn conversations as well as individual turns and spans.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Phoenix supports sessions, session-level annotations, and whole-conversation evaluation.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Agent-trajectory evaluation<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes, including task completion, trajectory accuracy, and tool-correctness metrics.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes, through trace evaluation, tool-calling evaluators, and custom evaluators over agent traces.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">AI engineering assistant<\/td><td class=\"has-text-align-left\" data-align=\"left\">Ollie investigates traces, searches across projects, manages Test Suites, and works with prompts, datasets, experiments, and conversations. Ollie is available on all cloud plans including the free tier but is not currently available in OSS. <\/td><td class=\"has-text-align-left\" data-align=\"left\">PXI, currently documented as beta, investigates traces, prompts, evaluations, datasets, and experiments; it can propose prompt diffs, run experiments, and annotate data.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Automatic prompt optimization<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Multiple interchangeable optimizer families run behind a shared API, including MetaPrompt, HRPO, Few-Shot Bayesian, Evolutionary, GEPA, and Parameter Optimization. Results are also available in the UI.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Phoenix\u2019s Prompt Learning SDK iteratively improves prompts using evaluation feedback and a meta-prompt workflow.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Tool and MCP optimization<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Opik can optimize prompts that use function calls, external tools, and MCP servers.<\/td><td class=\"has-text-align-left\" data-align=\"left\">No equivalent first-party tool or MCP optimization workflow is clearly documented in Phoenix.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Framework coverage<\/td><td class=\"has-text-align-left\" data-align=\"left\">Framework-neutral<\/td><td class=\"has-text-align-left\" data-align=\"left\">Broad: OpenAI, Anthropic, CrewAI, Vercel AI SDK, Pydantic AI, and deepest with LangChain and LangGraph<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Multimodal tracing<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\"> Yes: Images, video, audio, text, PDFs, JSON, and arbitrary file attachments can be associated with traces and previewed in the UI.<\/td><td class=\"has-text-align-left\" data-align=\"left\">Phoenix documents displaying images included in LLM traces.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Multimodal evaluation and optimization<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Online evaluation can score image-based traces, and all six documented prompt optimizer families can pass text-and-image content to compatible models.<\/td><td class=\"has-text-align-left\" data-align=\"left\">Broader image, voice, and PDF evaluation is listed for Arize AX; an equivalent breadth is not clearly documented for Phoenix OSS.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Disk-backed ingestion fallback<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">The Python SDK automatically writes failed messages to a local SQLite database during outages and transparently replays them after connectivity returns.<\/td><td class=\"has-text-align-left\" data-align=\"left\">No equivalent SDK-level, disk-backed replay mechanism is documented. Phoenix production guidance instead focuses on OpenTelemetry exporter, collector, batching, database, and deployment configuration.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Embedding and retrieval visualization<\/td><td class=\"has-text-align-left\" data-align=\"left\">RAG traces and retrieval quality can be evaluated, but a dedicated embeddings-cluster visualizer is not a central documented workflow.<\/td><td class=\"has-text-align-left\" data-align=\"left\"><img decoding=\"async\" src=\"https:\/\/dev-comet-marketing-site.pantheonsite.io\/wp-content\/uploads\/2025\/08\/check-in-circle.svg\" alt=\"checkmark\">Yes. Phoenix includes an embeddings visualizer for understanding clustering, representation, indexing, and search relevance.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<div class=\"wp-block-group has-body-xs-font-size is-layout-constrained wp-block-group-is-layout-constrained\">\n<p class=\"has-text-align-left wp-block-paragraph\">One clarification on testing is important. Phoenix does support serious regression testing. Its pytest integration can map test cases to Phoenix datasets, record each run as an experiment, attach scores, preserve Git metadata, and fail CI using ordinary assertions. Opik\u2019s advantage is not that Phoenix lacks testing; it is that Opik makes Test Suites a native product object that can be built and managed from the UI, SDK, or Ollie without requiring developers to design the workflow around an external test runner.<\/p>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\">The same caveat applies to production. Phoenix can receive and evaluate production traces. The difference is that Phoenix\u2019s documentation points teams to Arize AX for continuous monitoring with alerts, managed compute, custom dashboards, and operational support. Opik exposes production-scale monitoring, online evaluation, and webhook alerts in its open-source plan.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group alignfull has-custom-alt-background-dark-background-color has-background is-layout-constrained wp-container-core-group-is-layout-e5a791a7 wp-block-group-is-layout-constrained\" style=\"border-top-color:var(--wp--preset--color--custom-decorative-border-dark);border-top-width:1px;border-bottom-color:var(--wp--preset--color--custom-decorative-border-dark);border-bottom-width:1px;margin-top:var(--wp--preset--spacing--100);margin-bottom:var(--wp--preset--spacing--100);padding-top:var(--wp--preset--spacing--100);padding-bottom:var(--wp--preset--spacing--100)\">\n<div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-left has-display-s-font-size\"><strong>Can you self-host Arize Phoenix or Opik?<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Yes. Both can be deployed on a laptop, private cloud, Kubernetes cluster, on-premises environment, or isolated network.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Opik\u2019s self-hosted product uses Apache License 2.0 and includes the full observability and agent-testing feature set. The license allows teams to use, modify, distribute, and build commercial services around the software under Apache\u2019s standard conditions.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Phoenix is also free to self-host, with no Phoenix features held back for a paid Phoenix edition. However, Arize AX has a different feature set and you are upgrading to a different core product, whereas Opik&#8217;s open-source version shares a nearly identical codebase with the cloud and enterprise versions, making upgrades smoother. With Phoenix, your team is responsible for provisioning, scaling, upgrading, securing, and supporting the deployment. Phoenix\u2019s Elastic License 2.0 permits internal use and modification but restricts providing a substantial part of Phoenix to third parties as a hosted or managed service.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For most internal engineering teams, both products satisfy the basic requirement to keep trace and evaluation data inside their own infrastructure. Apache-2.0 becomes more important when permissive redistribution, product embedding, or commercial hosting rights matter.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-left has-display-s-font-size\">Is Opik a good open-source alternative to Arize Phoenix?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Yes, particularly for teams that want to move from observing an agent to systematically improving it without assembling separate workflows for testing, production evaluation, optimization, and regression prevention.<br><br>Opik covers the core Phoenix use cases: tracing, datasets, experiments, deterministic evaluation, LLM-as-a-judge, human review, production monitoring, prompt management, and self-hosted deployment. It then adds native Test Suites, built-in online-evaluation rules and alerts, disk-backed outage recovery in the Python SDK, broader documented multimodal support, and optimization for prompts, parameters, tools, and MCP workflows.<br><br>Phoenix remains a compelling alternative when the architecture matters more than having every workflow consolidated in the product. Teams already operating OpenTelemetry collectors may prefer Phoenix\u2019s native gRPC support and OpenInference conventions. Teams working heavily on search and retrieval may also value its embeddings visualizer.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-left has-display-s-font-size\">Which has better evaluation?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Both platforms have credible evaluation systems, and reducing the comparison to a checklist would miss the more important difference.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Phoenix supports deterministic code evaluators, custom heuristics, LLM-as-a-judge, client-side evaluation in Python and TypeScript, server-side evaluators configured through the UI, evaluations over production traces, and evaluation runs linked back to their own OpenTelemetry traces. Its pytest integration is especially useful for teams that already treat evaluation code as part of the application\u2019s normal test suite.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Opik supports the same broad categories of evaluation, including offline experiments, online production evaluation, human review, conversation-level scoring, trajectory evaluation, and built-in or custom metrics. Its clearest advantage is the Test Suite abstraction: developers can express expected behavior as pass\/fail assertions, apply assertions globally or to individual scenarios, specify how many times nondeterministic cases must run, and define how many runs must pass. Test Suites can be created in the UI, called through the SDK, or populated from failed production traces by Ollie.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For a team that wants evaluation code to live primarily in pytest, Phoenix is a strong choice, though Opik\u2019s pytest integration is worth comparing too. For a broader group of developers, product managers, and domain experts who need to build and inspect regression suites inside the observability platform, Opik provides the more integrated workflow.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Opik also goes further once the evaluation identifies a problem. Its optimizer can search multiple prompt strategies, model parameters, few-shot examples, tool definitions, and MCP workflows against the same datasets and evaluation metrics. Phoenix offers automatic prompt learning, but its documented optimization scope is narrower.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group alignfull is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<h2 class=\"wp-block-heading has-text-align-center\"><strong>How do Arize Phoenix and Opik pricing compare?<\/strong><\/h2>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\">Both self-hosted products are free. The hosted comparison requires one clarification: <strong>Phoenix does not have a paid hosted Phoenix plan. Arize AX is the separate managed product teams use when they no longer want to operate Phoenix themselves.<\/strong><br><\/p>\n<\/div>\n\n\n\n<figure class=\"wp-block-table alignfull feature-table is-style-stripes unstyled-links\"><table class=\"has-background-color has-text-color has-link-color has-fixed-layout\" style=\"border-style:none;border-width:0px\"><thead><tr><th class=\"has-text-align-left\" data-align=\"left\">Tier<\/th><th class=\"has-text-align-left\" data-align=\"left\">Opik (by Comet)<\/th><th class=\"has-text-align-left\" data-align=\"left\">LangSmith (by LangChain)<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-left\" data-align=\"left\">Self-hosted<\/td><td class=\"has-text-align-left\" data-align=\"left\">$0. Full open-source observability and agent-testing feature set under Apache-2.0.<\/td><td class=\"has-text-align-left\" data-align=\"left\">$0. Phoenix is self-hosted with no feature-gated Phoenix edition, under ELv2.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Free cloud<\/td><td class=\"has-text-align-left\" data-align=\"left\"><strong>Opik Free Cloud: $0, 25,000 spans per month, up to 10 team members, and 60-day retention.<\/strong><\/td><td class=\"has-text-align-left\" data-align=\"left\"><strong>Arize AX Free: $0, 25,000 spans per month, 1 GB of monthly ingestion, unlimited users and evaluations, and 15-day retention.<\/strong><\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Entry paid cloud<\/td><td class=\"has-text-align-left\" data-align=\"left\">Opik Pro Cloud: $19 per month, 100,000 spans per month, up to 50 team members, and 60-day retention.<\/td><td class=\"has-text-align-left\" data-align=\"left\">Arize AX Pro: $50 per month, 50,000 spans per month, 10 GB of monthly ingestion, unlimited users and evaluations, and 30-day retention.<\/td><\/tr><tr><td class=\"has-text-align-left\" data-align=\"left\">Enterprise<\/td><td class=\"has-text-align-left\" data-align=\"left\">Custom usage and retention, flexible deployments, SSO, service accounts, dedicated support, SLAs, and compliance options.<\/td><td class=\"has-text-align-left\" data-align=\"left\">Custom. Arize AX supports SaaS or commercially licensed self-hosting, custom usage, managed infrastructure, enterprise support, and SLAs.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Current public pricing makes Opik\u2019s hosted entry point less expensive and includes more spans and longer retention at the first paid tier. Arize AX includes unlimited users and evaluations on its free and Pro plans and meters both spans and ingestion storage, so the packages are not perfectly equivalent.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For self-hosting, price is not the meaningful distinction: both cost $0 in license fees. The relevant comparison is Apache-2.0 versus ELv2, the operational work your team must take on, and whether the capabilities you need are present in the self-hosted product or require moving to a separate managed platform<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group alignfull has-custom-alt-background-dark-background-color has-background is-layout-constrained wp-container-core-group-is-layout-e5a791a7 wp-block-group-is-layout-constrained\" style=\"border-top-color:var(--wp--preset--color--custom-decorative-border-dark);border-top-width:1px;border-bottom-color:var(--wp--preset--color--custom-decorative-border-dark);border-bottom-width:1px;margin-top:var(--wp--preset--spacing--100);margin-bottom:var(--wp--preset--spacing--100);padding-top:var(--wp--preset--spacing--100);padding-bottom:var(--wp--preset--spacing--100)\">\n<div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-left has-display-s-font-size\">Do Arize Phoenix and Opik offer free trials or proof of concept?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Neither platform requires a sales conversation to begin a self-hosted proof of concept.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Opik\u2019s full open-source deployment is free, and Opik Cloud has a $0 tier with 25,000 spans per month. Phoenix is also free to self-host with no Phoenix feature gates. Teams that prefer Arize\u2019s managed platform can start on the separate AX Free plan.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A useful proof of concept should test more than whether both products can display the same trace. Instrument one representative production agent and compare four complete workflows:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Identify the root cause of a failed or low-quality output.<\/li>\n\n\n\n<li>Turn that failure into a repeatable regression test.<\/li>\n\n\n\n<li>Evaluate the behavior continuously on production traffic.<\/li>\n\n\n\n<li>Improve the agent and verify that the change did not create a new regression.<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">Also simulate a temporary network failure. Opik\u2019s Python SDK should persist failed tracing messages locally and replay them after recovery. With Phoenix, review how your chosen OpenTelemetry exporter, processor, collector, and queue configuration behave under the same conditions.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The platform that makes the entire loop easiest for your team\u2014not merely the one with the best trace screenshot\u2014is usually the right choice.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<h2 class=\"wp-block-heading has-text-align-left has-display-s-font-size\">How do you get started with Opik?<\/h2>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\">Three steps are enough to begin tracing an application:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Install the SDK: pip install opik<\/li>\n\n\n\n<li>Add the @track decorator or enable the integration for your framework.<\/li>\n\n\n\n<li>Open the trace view and inspect your application\u2019s recent executions.<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">From there, select a failed trace and add it to a Test Suite. Define the expected behavior as an assertion, run the suite against the current application, and preserve the case as a regression test.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Teams using Opik Cloud can begin on the free plan. Teams that need local data storage can launch the open-source deployment through the provided self-hosting script or use the Kubernetes Helm chart.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-left has-display-s-font-size\"><strong><strong>Where does Arize Phoenix beat Opik?<\/strong><\/strong><\/h2>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\">There are three places where Phoenix has a genuine advantage.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">First, Phoenix has the deeper OpenTelemetry and OpenInference architecture. It supports OTLP over both HTTP and gRPC, uses OpenInference semantic conventions throughout the product, and is a natural fit for teams that already route telemetry through collectors and shared observability infrastructure. Opik accepts native OpenTelemetry traces from many languages, but its documented direct integration currently supports HTTP transport only.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Second, Phoenix has especially strong search and retrieval tooling. Its embeddings visualizer helps teams examine how data is clustered and represented, which can inform chunking, indexing, similarity, and retrieval decisions. Teams building retrieval-intensive applications may value that visual workflow more than Opik\u2019s broader optimization surface.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Third, Phoenix fits naturally into existing software-testing conventions. Its pytest plugin lets developers write evaluation cases as ordinary tests, use fixtures and parameterization, preserve Git metadata, run the same suite locally or in CI, and fail the build through standard assertions. Opik\u2019s native Test Suites require fewer moving parts inside the product, but teams already committed to test-as-code may prefer Phoenix\u2019s approach.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">PXI is also a meaningful Phoenix strength. It can investigate failures, navigate observability data, propose prompt revisions, run experiments, and author evaluators from inside Phoenix. Ollie goes further into the application code, but PXI is not merely a chat interface layered over trace search.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-left has-display-s-font-size\"><strong><strong>Which should you choose?<\/strong><\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Choose <strong>Opik<\/strong> when your priorities are:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>A permissive Apache-2.0 license<\/li>\n\n\n\n<li>Native Test Suites that can be managed in the UI and SDK<\/li>\n\n\n\n<li>Production evaluation and alerts in the open-source product<\/li>\n\n\n\n<li>A unified workflow from failed trace to regression test<\/li>\n\n\n\n<li>Prompt, parameter, tool, MCP, and multimodal optimization<\/li>\n\n\n\n<li>Built-in SDK protection against temporary ingestion outages<\/li>\n\n\n\n<li>Broader collaboration across developers and non-developer evaluators<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Choose <strong>Arize Phoenix<\/strong> when your priorities are:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>OpenTelemetry and OpenInference as the foundation of your architecture<\/li>\n\n\n\n<li>Native OTLP over gRPC<\/li>\n\n\n\n<li>Tight integration with an existing pytest-based test workflow<\/li>\n\n\n\n<li>Embedding visualization and retrieval analysis<\/li>\n\n\n\n<li>A self-hosted platform your infrastructure team is prepared to operate<\/li>\n\n\n\n<li>A future path into Arize AX for managed GenAI and predictive-ML observability<\/li>\n<\/ul>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\">Both are capable observability and evaluation platforms. The decision is less about whether either product can capture a trace or run an LLM judge. It is about whether your team wants a standards-oriented toolkit that fits into existing telemetry and testing infrastructure, or a more integrated product for testing, monitoring, optimizing, and fixing agents.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group alignwide is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-center\"><strong><strong><strong>Frequently asked questions<\/strong><\/strong><\/strong><\/h2>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\" style=\"margin-top:var(--wp--preset--spacing--100);margin-bottom:var(--wp--preset--spacing--100)\">\n<div class=\"wp-block-comet-accordion-accordion comet-accordion\" data-allow-multiple=\"true\">\n<details class=\"wp-block-comet-accordion-item comet-accordion__item\" open><summary class=\"comet-accordion__item-summary\"><h3><strong>Is Opik really free, or is it open core?<\/strong><\/h3><span class=\"comet-accordion__item-icon\" aria-hidden=\"true\"><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"16\" height=\"16\" fill=\"none\" stroke=\"#191A1C\"><path stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"M8 1v14m7-7H1\"><\/path><\/svg><\/span><\/summary><div class=\"comet-accordion__item-content\">\n<p class=\"wp-block-paragraph\">Opik\u2019s repository is licensed under Apache License 2.0, and the open-source deployment includes the full AI observability and agent-testing feature set rather than a reduced community edition. Tracing, Test Suites, datasets, experiments, online evaluation, alerts, multimodal logging, and agent optimization are listed for the open-source plan.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Paid plans primarily provide hosted infrastructure, higher usage limits, longer or configurable retention, enterprise identity features, support, SLAs, and compliance options. Opik Connect\u2019s repository-aware code-editing and rerun features are listed separately from the open-source tier.<\/p>\n<\/div><\/details>\n\n\n\n<details class=\"wp-block-comet-accordion-item comet-accordion__item\" open><summary class=\"comet-accordion__item-summary\"><h3><strong><strong><strong>Is Arize Phoenix really open source?<\/strong><\/strong><\/strong><\/h3><span class=\"comet-accordion__item-icon\" aria-hidden=\"true\"><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"16\" height=\"16\" fill=\"none\" stroke=\"#191A1C\"><path stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"M8 1v14m7-7H1\"><\/path><\/svg><\/span><\/summary><div class=\"comet-accordion__item-content\">\n<p class=\"wp-block-paragraph\">Arize describes Phoenix as an open-source platform with no gated Phoenix features, and the full source code can be inspected, modified, and self-hosted. Phoenix uses Elastic License 2.0 rather than Apache-2.0. ELv2 permits broad use and modification but restricts providing a substantial set of Phoenix functionality to third parties as a hosted or managed service.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For an internal self-hosted deployment, that restriction may make little practical difference. It matters more to vendors embedding the platform into a commercial product or offering it as a service.<\/p>\n<\/div><\/details>\n\n\n\n<details class=\"wp-block-comet-accordion-item comet-accordion__item\" open><summary class=\"comet-accordion__item-summary\"><h3><strong><strong><strong><strong><strong><strong><strong><strong>Can Phoenix run in production?<\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/h3><span class=\"comet-accordion__item-icon\" aria-hidden=\"true\"><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"16\" height=\"16\" fill=\"none\" stroke=\"#191A1C\"><path stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"M8 1v14m7-7H1\"><\/path><\/svg><\/span><\/summary><div class=\"comet-accordion__item-content\">\n<p class=\"wp-block-paragraph\">Yes. Phoenix documentation explicitly says that the platform can run in production. Your team is responsible for the deployment, scaling, upgrades, database, availability, and support.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Arize recommends AX when teams need managed infrastructure, automatic scaling, production alerting, custom dashboards, large evaluation compute, dedicated support, or SLAs.<\/p>\n<\/div><\/details>\n\n\n\n<details class=\"wp-block-comet-accordion-item comet-accordion__item\" open><summary class=\"comet-accordion__item-summary\"><h3><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong>Does Opik support OpenTelemetry?<\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/h3><span class=\"comet-accordion__item-icon\" aria-hidden=\"true\"><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"16\" height=\"16\" fill=\"none\" stroke=\"#191A1C\"><path stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"M8 1v14m7-7H1\"><\/path><\/svg><\/span><\/summary><div class=\"comet-accordion__item-content\">\n<p class=\"wp-block-paragraph\">Yes. Opik can ingest native OpenTelemetry traces and accepts data from OpenTelemetry SDKs across languages including Java, JavaScript, Go, .NET, Ruby, Rust, Python, and others.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The current documented difference is transport: Opik\u2019s direct OpenTelemetry integration supports HTTP, while Phoenix supports both HTTP and gRPC.<\/p>\n<\/div><\/details>\n\n\n\n<details class=\"wp-block-comet-accordion-item comet-accordion__item\" open><summary class=\"comet-accordion__item-summary\"><h3><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong>Can I move from Phoenix to Opik?<\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/h3><span class=\"comet-accordion__item-icon\" aria-hidden=\"true\"><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"16\" height=\"16\" fill=\"none\" stroke=\"#191A1C\"><path stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"M8 1v14m7-7H1\"><\/path><\/svg><\/span><\/summary><div class=\"comet-accordion__item-content\">\n<p class=\"wp-block-paragraph\">Because both products accept OpenTelemetry data, the lowest-risk approach is to send new traces to both platforms during a limited parallel evaluation. Configure an HTTP OTLP exporter for Opik and keep the existing Phoenix exporter active until the Opik traces, metadata, and evaluation workflows have been validated.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Treat historical data migration separately from new trace routing. Validate the fields, span semantics, attachments, annotations, datasets, and evaluation records that need to be retained before decommissioning the original deployment.<\/p>\n<\/div><\/details>\n\n\n\n<details class=\"wp-block-comet-accordion-item comet-accordion__item\" open><summary class=\"comet-accordion__item-summary\"><h3><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong><strong>Which platform is better for agent optimization?<\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/strong><\/h3><span class=\"comet-accordion__item-icon\" aria-hidden=\"true\"><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"16\" height=\"16\" fill=\"none\" stroke=\"#191A1C\"><path stroke-linecap=\"round\" stroke-linejoin=\"round\" stroke-width=\"2\" d=\"M8 1v14m7-7H1\"><\/path><\/svg><\/span><\/summary><div class=\"comet-accordion__item-content\">\n<p class=\"wp-block-paragraph\">Opik has the broader documented optimization system. Its optimizer provides several interchangeable algorithm families and supports prompt rewriting, few-shot selection, model-parameter search, tool definitions, function calling, MCP workflows, and multimodal prompts.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Phoenix supports automatic prompt optimization through its Prompt Learning SDK. That is a meaningful capability, but equivalent first-party workflows for tool, MCP, parameter, and multimodal optimization are not currently documented at the same breadth.<\/p>\n<\/div><\/details>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group has-border-color has-custom-decorative-border-dark-border-color has-background-color has-text-color has-link-color wp-elements-2 is-layout-flow wp-block-group-is-layout-flow has-background\" style=\"border-width:1px;border-top-left-radius:8px;border-top-right-radius:8px;border-bottom-left-radius:8px;border-bottom-right-radius:8px;margin-top:var(--wp--preset--spacing--100);margin-bottom:var(--wp--preset--spacing--100);padding-top:var(--wp--preset--spacing--40);padding-right:var(--wp--preset--spacing--40);padding-bottom:var(--wp--preset--spacing--40);padding-left:var(--wp--preset--spacing--40);background-image:var(--wp--preset--gradient--custom-dark-background);\">\n<h2 class=\"wp-block-heading has-text-align-left\"><strong><strong><strong><strong>Try Opik<\/strong><\/strong><\/strong><\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Free and open source, self-hosted or managed, whether you are debugging your first agent or running hundreds in production.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong><a href=\"https:\/\/www.comet.com\/signup?from=llm\">Free cloud signup<\/a><\/strong><\/li>\n\n\n\n<li><strong>Self-host:<\/strong> <a href=\"https:\/\/github.com\/comet-ml\/opik\">github.com\/comet-ml\/opik<\/a><\/li>\n\n\n\n<li><strong>Docs:<\/strong> <a href=\"https:\/\/www.comet.com\/docs\/opik\/\">comet.com\/docs\/opik<\/a><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Its annotation and human-feedback tooling is mature and well documented, and it has been in production use longer.<\/p>\n\n\n\n<p class=\"has-text-align-left wp-block-paragraph\">And if you want a fully managed service and have no self-hosting requirement, a single-vendor SaaS with no infrastructure to run is a legitimate preference, not a compromise.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>Teams with compliance or deployment requirements can talk to us about Enterprise, but you do not need to in order to run the whole thing.<\/em><\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group alignwide is-layout-constrained wp-container-core-group-is-layout-f88ee8fa wp-block-group-is-layout-constrained\" style=\"padding-top:var(--wp--preset--spacing--100);padding-bottom:var(--wp--preset--spacing--100)\">\n<div class=\"wp-block-group alignwide testimonial-card has-border-color has-custom-decorative-border-dark-border-color has-secondary-color has-custom-alt-background-dark-background-color has-text-color has-background has-link-color wp-elements-3 is-vertical is-nowrap is-layout-flex wp-container-core-group-is-layout-2af0c81c wp-block-group-is-layout-flex\" style=\"border-width:1px;border-radius:12px\">\n<div class=\"wp-block-group wp-container-content-c795c25f is-vertical is-layout-flex wp-container-core-group-is-layout-cc9b9dd5 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-full is-resized\"><a href=\"https:\/\/www.comet.com\/site\/customers\/pattern-ai-content-analysis\/\"><img loading=\"lazy\" decoding=\"async\" width=\"180\" height=\"36\" src=\"https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/10\/pattern-logo-white.svg\" alt=\"pattern company logo \" class=\"wp-image-18104\" style=\"object-fit:contain;width:140px;height:42px\"\/><\/a><\/figure>\n<\/div>\n\n\n\n<p class=\"has-background-color has-text-color has-link-color has-body-m-font-size wp-elements-4 wp-container-content-9cfa9a5a wp-block-paragraph\">&#8220;Opik being open-source was one of the reasons we chose it. Beyond the peace of mind of knowing we can self-host if we want, the ability to debug and submit product requests when we notice things has been really helpful in making sure the product meets our needs.\u201d<\/p>\n\n\n\n<div class=\"wp-block-group vc-testimonial-block__source is-flex is-vertical is-nowrap is-layout-flex wp-container-core-group-is-layout-3c019351 wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-image size-thumbnail is-resized size-full is-style-rounded flex-shrink-0\"><img loading=\"lazy\" decoding=\"async\" width=\"150\" height=\"150\" src=\"https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/02\/Jeremy-Mumford-sq-1-150x150.jpg\" alt=\"Jeremy Mumford\" class=\"wp-image-16525\" style=\"object-fit:cover;width:68px;height:68px\" srcset=\"https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/02\/Jeremy-Mumford-sq-1-150x150.jpg 150w, https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/02\/Jeremy-Mumford-sq-1-300x300.jpg 300w, https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/02\/Jeremy-Mumford-sq-1-768x768.jpg 768w, https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/02\/Jeremy-Mumford-sq-1.jpg 1000w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/figure>\n\n\n\n<div class=\"wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-d62794ec wp-block-group-is-layout-flex\">\n<p class=\"has-accent-color has-text-color has-link-color wp-elements-5 wp-block-paragraph\" style=\"text-transform:uppercase\"><strong>Jeremy Mumford<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\" style=\"text-transform:uppercase\"><strong>Lead AI Engineer, <a href=\"https:\/\/www.comet.com\/site\/customers\/pattern-ai-content-analysis\/\">Pattern<\/a><\/strong><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group alignfull is-layout-constrained wp-block-group-is-layout-constrained\" style=\"margin-top:0;margin-bottom:0;padding-top:var(--wp--preset--spacing--100);padding-bottom:var(--wp--preset--spacing--100)\">\n<div class=\"wp-block-group alignwide has-background-color has-accent-background-color has-text-color has-background has-link-color wp-elements-6 is-layout-constrained wp-container-core-group-is-layout-fb75a317 wp-block-group-is-layout-constrained\" style=\"border-radius:12px;padding-top:var(--wp--preset--spacing--50);padding-right:var(--wp--preset--spacing--50);padding-bottom:var(--wp--preset--spacing--50);padding-left:var(--wp--preset--spacing--50);background-image:url(&apos;https:\/\/www.comet.com\/site\/wp-content\/uploads\/2025\/03\/pattern-4.png&apos;);background-position:50% 50%;background-size:cover;background-attachment:scroll;\">\n<h2 class=\"wp-block-heading has-text-align-center has-background-color has-text-color has-link-color wp-elements-7\" id=\"h-get-started-today-for-free\" style=\"margin-top:var(--wp--preset--spacing--24)\">Ready to Upgrade Your AI Development Workflows?<\/h2>\n\n\n\n<p class=\"has-text-align-center has-body-m-font-size wp-block-paragraph\">Join the growing number of developers who&#8217;ve turned to Opik for superior performance, flexibility, and advanced features when building AI applications.<\/p>\n\n\n\n<div class=\"wp-block-buttons is-content-justification-center is-layout-flex wp-container-core-buttons-is-layout-43139366 wp-block-buttons-is-layout-flex\" style=\"margin-bottom:var(--wp--preset--spacing--24)\">\n<div class=\"wp-block-button\"><a rel=\"\" target=\"\" class=\"wp-block-button__link has-tertiary-background-color has-background wp-element-button\" href=\"https:\/\/www.comet.com\/signup?from=llm\">Create Free Account<\/a><\/div>\n\n\n\n<div class=\"wp-block-button is-style-underline\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/www.comet.com\/site\/about-us\/contact-us\/\">Contact Sales<\/a><\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Arize Phoenix vs. Opik: Open-Source AI Agent Observability and LLM Evaluation in 2026 Last updated: 2026-08-31 \u2728 The short answer: Choose Opik if you want the more permissive Apache-2.0 license, native Test Suites, production evaluation and alerts in the open-source product, broader multimodal workflows, and optimization that extends beyond prompts to tools and agents. Choose [&hellip;]<\/p>\n","protected":false},"author":132,"featured_media":19027,"parent":17633,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"wp-custom-template-pages-dark","meta":{"customer_name":"","customer_description":"","customer_industry":"","customer_technologies":"","customer_logo":"","footnotes":""},"coauthors":[125],"class_list":["post-18805","page","type-page","status-publish","has-post-thumbnail","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v25.9 (Yoast SEO v25.9) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Opik vs. Phoenix: Side-by-Side Comparison<\/title>\n<meta name=\"description\" content=\"Discover the feature breakdown between Opik and Phoenix for LLM evaluation requirements.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" 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