Braintrust
Free tierThe AI observability platform for building quality AI products at scale
Free tier available·All audiences·API available
Key strengths
Real-time trace inspection for prompts, responses, and tool callsAutomated pattern discovery via Topics clusteringFlexible eval scoring with LLMs, code, or human reviewersCustom-built Brainstore database optimized for AI trace data at scaleQuality gates that block bad releases before they hit production
Free tier + paid plans
US
Self-hostable
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- Distributed agent tracing — Instrument multi-step agent workflows with span-level tracing to inspect every LLM call, tool invocation, and retrieval step individually.
- Automated online scoring — Configure continuous scorers that evaluate production outputs in real time, triggering alerts or quality gates when scores drop below thresholds.
- Prompt & model experimentation — Run versioned eval experiments against curated datasets, comparing prompts and model configurations with reproducible, side-by-side scoring.
- Trace-to-dataset pipeline — Automatically promote production traces to labeled datasets for regression testing, closing the loop between observability and evaluation.
- MCP server integration — Connect coding agents (e.g., Cursor) to Braintrust via the MCP server to query logs, run evals, and push prompt updates directly from the IDE.
- Custom facet & annotation UIs — Define business-specific dimensions (compliance, tone, customer segment) and build task-specific annotation interfaces without any frontend engineering.