Langfuse

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, evaluation, and agent testing.

An open-source platform for monitoring, evaluating, and testing LLM and agent applications. LangWatch captures traces, runs evaluations and simulations, and surfaces quality and cost metrics in production. Offered as managed cloud or fully self-hosted for teams with strict data-residency needs.

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.

Open-source LLM evaluation, tracing, and monitoring.

Open-source platform from Comet for debugging and evaluating LLM and agent apps: full tracing of calls, tools, and agent steps, LLM-as-a-judge and heuristic evals, prompt management, and production dashboards. Self-host via Docker or Kubernetes, or use Comet's hosted cloud.