Arize Phoenix vs Langfuse vs Opik vs LangSmith
A side-by-side look at scores, pricing and features — with RECATOOLS' ASEAN-aware verdict for each.
Arize Phoenix
Open-source LLM evaluation and observability
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Langfuse
Open-source LLM observability and analytics
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Opik
Open-source LLM tracing, evals and guardrails you can self-host
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LangSmith
LLM observability and evaluation from the LangChain team
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| RECATOOLS Score | 7.8 / 10 | 8.4 / 10 | 7.8 / 10 | 7.9 / 10 |
| Capability | ||||
| Value for money | ||||
| Ease of use | ||||
| ASEAN readiness | ||||
| API quality | ||||
| Pricing | Open Source | Open Source | Open Source | Freemium |
| Free tier | — | — | — | — |
| Paid from | — | — | — | — |
| Has API | ✓ | ✓ | ✓ | ✓ |
| Open source | ✓ | ✓ | ✓ | ✗ |
| Free to use | ✓ | ✓ | ✓ | ✓ |
| Users | — | — | — | — |
| Founded | 2023 | 2023 | — | 2023 |
| Maker | — | — | — | — |
| Verdict | Arize Phoenix is an open-source observability and evaluation toolkit for LLM and AI applications, offering tracing, prompt and RAG debugging, evals, and OpenTelemetry-based instrumentation that runs locally or self-hoste... |
Langfuse is a leading open-source LLM observability platform covering tracing, prompt management, evaluations, cost tracking and analytics, with framework-agnostic SDKs that work well alongside LangChain, LlamaIndex or r... |
Opik is the rare open-source LLM observability tool where the free self-hosted version isn't a stripped-down teaser — Comet's own docs describe it as the same codebase as the hosted product. Tracing, LLM-as-a-judge evalu... |
LangSmith is LangChain's first-party platform for tracing, debugging, evaluating and monitoring LLM applications, with the tightest integration into LangChain and LangGraph of any observability tool. It suits teams alrea... |
| Full review → | Full review → | Full review → | Full review → |
Comparisons cover up to 4 tools. Scores are RECATOOLS editorial assessments; verify current pricing on each vendor's site.