Pydantic Logfire

Open-source LLM observability. Self-hostable, OpenTelemetry-native.

Tracing, evals, prompt management, and dataset tooling for LLM apps — self-host on your own infra or use Langfuse Cloud. The open-source default when you want full ownership of your observability stack.

Drop-in LLM proxy with logging, caching, and cost tracking.

One-line integration — change your OpenAI/Anthropic base URL and get a dashboard with every prompt, response, latency, and dollar tracked. Adds caching and rate-limit handling without code changes.

LangChain's hosted observability + eval platform.

Tracing, dataset management, eval orchestration, and prompt playground from the LangChain team. Pairs naturally if LangChain or LangGraph already runs in your stack, but works standalone via SDKs.

LLM observability built on OpenTelemetry.

A reliability platform for LLM apps: its open-source OpenLLMetry SDK instruments LLM, vector-DB, and framework calls as standard OpenTelemetry spans, which Traceloop's hosted dashboard turns into traces, cost/latency analytics, and quality monitoring. Because the data is plain OTel, you can pipe it to existing observability stacks instead of a proprietary one.