Library / SDK
Observability & EvaluationRetrieval & Memory
TruLens
1Evaluate 2and 3track 4LLM 5app 6experiments
the six Ws · specification
W1
Who
Maintained by TruEra (now part of Snowflake).
W2
What
A library for evaluating and tracking LLM apps using programmatic feedback functions.
W3
Where
A Python library run locally with a local dashboard.
W4
When
Reach for it when iterating on RAG and agent quality with quantitative feedback.
W5
Why
Feedback functions give measurable scores to compare app versions.
W6
With
Integrates with LangChain, LlamaIndex, and OpenAI.
W7
Watch
Originated at TruEra (acquired by Snowflake); open-source (MIT) library, self-hostable. Feedback functions may call whatever provider you configure.
alternatives