LangSmith

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.

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.

OpenTelemetry-based observability for LLM apps and agents.

Langtrace is an open-source observability and evaluation platform for LLM applications, capturing traces, token usage, latency, and cost across popular models, frameworks, and vector databases. Because it emits standard OpenTelemetry spans, traces flow to any OTel-compatible backend, and instrumentation is a two-line SDK install in Python or TypeScript. It ships as a hosted cloud with a free tier plus a self-hostable / on-prem option for data-sensitive teams.

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.