Tracing & Monitoring

See inside a running agent — every LLM call, tool use, latency, and cost — with dashboards and alerts to catch regressions in production.

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Open-source LLM and agent observability — OpenTelemetry tracing and evals you can self-host

arize-phoenix-v20.8.02026-09-04PythonElastic-2.0
11.4k Open source Free tier Paid
Helicone

Helicone

Helicone

Open-source LLM observability via a one-line proxy — logging, caching, and cost tracking

No updates in 1+ yearv2025.08.21-12025-08-21TypeScriptApache-2.0
6.1k Open source Free tier Paid
Langfuse

Langfuse

Langfuse

Open-source tracing, evaluation, and analytics for LLM and agent applications

v4.30.02026-09-04TypeScriptMIT
34.3k Open source Free tier Paid
LangSmith

LangSmith

LangChain

LangChain's hosted platform for tracing, evaluating, and monitoring LLM and agent apps (works with or without LangChain)

SaaS / SDKProprietary
Free tier Paid
Opik

Opik

Comet

Comet's open-source platform for tracing, evaluating, and monitoring LLM apps

v2.2.532026-09-07PythonApache-2.0
21.8k Open source Free tier Paid