Helicone

LiteLLM provides a unified interface and proxy gateway for LLM calls, simplifying multi-model switching, routing, and cost control.

Langfuse is an open-source observability platform for LLM applications, supporting tracing, evaluation, prompt versioning, and cost analytics.

DeepEval is an open-source evaluation framework for LLM applications. It provides rich evaluation metrics and tools, supporting unit testing and integration testing to help developers build reliable LLM applications.

TruLens is an open-source tool for evaluating and tracking LLM apps. It provides specialized evaluation for RAG applications including context relevance, groundedness, and answer relevance.