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Braintrust

Freemium

Eval-first LLM observability platform. Built around the experiment loop — define scorers, run prompt variations, compare versions, block CI merges when quality regresses. Closed-source SaaS used by Perplexity, Notion, Stripe, and Zapier for prompt regression testing. Tracing exists, but it's there to feed evaluation, not to stand alone as a production debugger.

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Pricing

Freemium

Type

Automation

Languages

Python, TypeScript

// VERDICT

Reach for Braintrust when you want a managed eval workflow - datasets, experiments, scoring and side-by-side comparison in a UI - for iterating on LLM features. Skip it when you prefer free, code-only evals (DeepEval/promptfoo) or don't need a platform.

Best for

A hosted platform for evaluating and iterating on LLM apps - datasets, experiments, scoring and a UI to compare versions, plus logging of production runs to grow eval sets.

Avoid when

You want a free/open-source code-only tool, or you don't need a managed UI and datasets.

CI/CD fit

SDK + CI integration · eval experiments · logging

Languages

Python · TypeScript

Team fit

LLM product teams · Dev/QA iterating on prompts/models · Teams wanting managed evals

Setup

Easy

Maintenance

Low

Learning

Intermediate

Licence

Freemium

// BEST FOR

  • Managed datasets, experiments and scoring for LLM evals
  • Side-by-side comparison of prompt/model versions in a UI
  • Logging production runs to build eval datasets
  • Collaborating on evals across a team
  • Running evals from the SDK in CI
  • Tracking quality as you iterate

// AVOID WHEN

  • You want a free, code-only eval tool
  • A managed platform isn't needed
  • You can't send data to a hosted service
  • Open-source self-hosting is required
  • Only simple prompt comparison is needed (PromptFoo)
  • You're not building LLM features

// QUICK START

npm install braintrust   # or pip install braintrust
// define datasets + scorers, run experiments via the SDK, compare in the UI;
// log production runs to grow eval sets, gate CI on scores

// ALTERNATIVES TO CONSIDER

ToolChoose it when
LangSmithYou want eval + tracing tied to the LangChain ecosystem.
DeepEvalYou prefer free, code-first evals as unit tests.
LangfuseYou want open-source eval + observability.

// FEATURES

  • Structured eval harness with custom scorers, statistical significance analysis, CI deployment blocking
  • AI Proxy with caching, retries, and failover across 100+ models
  • Interactive playground for prompt iteration on golden datasets derived from production logs
  • GitHub Actions and GitLab CI integration with PR comments and quality gates
  • Brainstore — OLAP database optimised for AI interaction queries

// PROS

  • Best-in-class for the regression workflow — 'did this change break behaviour X?' is what it's designed for
  • Auto-blocking on quality regression catches issues before deployment, not after
  • 1M trace spans and 10K evaluation runs free per month

// CONS

  • Closed-source — self-hosting requires Enterprise hybrid contract
  • Weaker agent-debugging UX than Laminar or LangSmith for long-running production traces
  • Pro plan starts at $249/month — not free past the trace-span threshold

// EXAMPLE QA WORKFLOW

  1. Wire the Braintrust SDK into your app

  2. Assemble datasets (and log production runs)

  3. Define experiments and scorers

  4. Run evals and compare versions in the UI

  5. Gate CI on scores/regressions

  6. Grow datasets from real traffic

// RELATED QA.CODES RESOURCES

Cheat sheets

Glossary