Braintrust
AI evaluation and observability platform focused on running structured evals, scoring LLM outputs, and prompt iteration workflows.
Why Braintrust?
Systematic eval-driven development — score outputs across test datasets
You want a managed product with a polished eval UI
Running A/B prompt experiments with statistical rigor
Signal Breakdown
What drives the Trust Score
Download Trend
Last 12 months
Tradeoffs & Caveats
Know before you commitBudget-constrained projects — paid tiers can get expensive
You only need basic tracing, not evals — Langfuse is simpler and free
Pricing
Free tier & paid plans
Free tier available
Team and Enterprise plans, custom pricing
Alternative Tools
Other options worth considering
Open-source LLM observability platform for tracing, evaluating, and debugging AI applications — self-host or use the cloud.
LangChain's observability and evaluation platform — trace, debug, and evaluate LLM applications with deep LangChain ecosystem integration.
Often Used Together
Complementary tools that pair well with Braintrust
Learning Resources
Docs, videos, tutorials, and courses
Get Started
Repository and installation options
npm install braintrustpip install braintrustQuick Start
Copy and adapt to get going fast
import * as braintrust from 'braintrust';
const experiment = braintrust.init('my-project', {
apiKey: process.env.BRAINTRUST_API_KEY,
experiment: 'gpt-4o-baseline',
});
experiment.log({
input: 'What is 2+2?',
output: '4',
expected: '4',
scores: { accuracy: 1.0 },
});Community Notes
Real experiences from developers who've used this tool