Freeplay

Hosted eval + tracing platform for LLM apps.

Production-grade eval orchestration with a dashboard, dataset versioning, and OpenTelemetry tracing. Useful once eval volume outgrows a CI YAML file.

Build, evaluate, and deploy production LLM apps and agents.

An end-to-end development platform for building, testing, and shipping LLM applications and agents. Vellum pairs a visual drag-and-drop workflow builder with a Python SDK, and bundles prompt versioning, RAG, evaluation, and production monitoring in one place so technical and non-technical teammates can collaborate. Built-in eval and test suites let teams measure quality before and after deploy. A free tier is available; paid Pro and Enterprise plans add seats and scale.

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.

The observability and evaluation layer for production AI agents.

A platform that unifies monitoring and testing for LLM apps and agents into one improvement loop: distributed tracing, online evaluations and alerts, offline experiments, annotation queues for expert feedback, and CI/CD-integrated regression testing. Built OpenTelemetry-native with support for 100+ models and agent frameworks. The free Developer tier covers small teams; Enterprise adds scale, self-host, and compliance.