The best LLM Observability & Evaluation
Every option ranked — open-source, self-hostable, and commercial — by our transparent Sovereignty Score, with honest trade-offs so you choose what fits you, not us.
Tracing, evaluation and cost tracking for LLM applications — hosted platforms compared against tools you can run yourself. What a request actually cost, why an answer was wrong, and whether a prompt change made things better.
L4Models & tooling — layer 4 of the AI stack- 1
Langfuse
Top pickOpen sourceThe self-hosted default for LLM tracing — MIT core, framework-agnostic.
Free to self-host — Docker Compose or Kubernetes, costs are your own infrastructure. A managed cloud with a free tier and paid plans exists if you would rather not run it. · in our LangSmith comparison →
What is Langfuse? →90sovereignty - 2
OpenLLMetry
Open sourceApache-2.0 OpenTelemetry instrumentation — send traces anywhere you already send them.
Free — Apache-2.0 instrumentation libraries. You pay only whatever backend you already send telemetry to; a hosted Traceloop backend is available separately. · in our LangSmith comparison →
What is OpenLLMetry? →92sovereignty - 3
Helicone
Open sourceGateway and observability in one — one integration instead of two.
Free and self-hostable under Apache-2.0. Hosted service has a free tier of roughly 10,000 requests per month, with paid plans starting around $79/month. · in our LangSmith comparison →
What is Helicone? →88sovereignty - 4
Phoenix (Arize)
CommercialStrong evaluation tooling — but read the licence before you build on it.
Free to self-host under ELv2 for your own internal use. Arize's commercial platform is priced separately. · in our LangSmith comparison →
What is Phoenix (Arize)? →62sovereignty
Is it free?
The free tier, its real limits and where you start paying — read from each vendor's own pricing page and dated.
Run these yourself
What each one actually needs — real RAM, honest running cost, and the setup time nobody quotes.
Replacing a specific tool?
Head-to-head comparisons for each popular llm observability & evaluation product.
Straight head-to-heads
Two llm observability & evaluation tools, side by side — verified facts and a plain verdict.