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
Free, self-hosted LLM tracing and evaluation
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Langfuse
Open-source LLM observability, tracing and evals
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Opik
Open-source LLM and agent tracing, evals and optimisation you can self...
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LangSmith
LangChain's platform for tracing, evaluating and deploying agents
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| RECATOOLS Score | 7.8 / 10 | 8.4 / 10 | 7.8 / 10 | 7.9 / 10 |
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| Value for money | ||||
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| ASEAN readiness | ||||
| API quality | ||||
| Pricing | Free | Freemium | Open Source | Freemium |
| Free tier | Self-host Phoenix free: no licence fees, usage limits or feature gates. Arize AX Free cloud tier: 25k spans, 1 GB ingest a month, 15-day retention | Self-host free under MIT (enterprise modules need a key); cloud Hobby plan free with 50k units/month, 30 days data access, 2 users | Apache-2.0 self-hosted version free with no span cap; Free Cloud $0: up to 10 members, 25k spans a month, 60-day retention | Developer: $0 for 1 seat with 5k base traces a month, then pay as you go |
| Paid from | Phoenix is free. Arize's managed AX Pro plan is $50/month | $29/month (Langfuse Cloud Core) | Pro Cloud $19/mo (100k spans, +$5 per extra 100k); Enterprise custom | $39/seat/month (Plus, 10k base traces a month included), then usage |
| Has API | ✓ | ✓ | ✓ | ✓ |
| Open source | ✓ | ✓ | ✓ | ✗ |
| Free to use | ✓ | ✓ | ✓ | ✓ |
| Users | — | — | — | — |
| Founded | 2023 | 2023 | 2024 | 2023 |
| Maker | Arize AI | ClickHouse, Inc. | Comet ML | LangChain Inc. |
| Verdict | Arize Phoenix is one of the most complete no-cost options for finding out why an agent or RAG pipeline behaved as it did: OpenTelemetry tracing, evals, datasets, experiments and a prompt playground, self-hosted with no f... |
Langfuse covers the core of LLM observability: nested traces with cost and latency, prompt versioning, datasets, experiments and LLM-as-judge evaluators, through framework-agnostic SDKs and OpenTelemetry. The MIT core se... |
Opik is one of the strongest open-source options for observing and evaluating LLM and agent applications: tracing, judge-based and heuristic evaluation, test suites, a playground and several prompt optimisers, under Apac... |
LangSmith is the most complete option for teams already on LangChain or LangGraph, where tracing works almost out of the box, and it is no longer tied to that stack: SDKs and OpenTelemetry bring in any framework. Evals,... |
| Full review → | Full review → | Directory listing → | Full review → |
Comparisons cover up to 4 tools. Scores are RECATOOLS editorial assessments; verify current pricing on each vendor's site.