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Braintrust vs Langfuse
Trust Score comparison · March 2026
Signal Comparison
12k / wknpm downloads160k / wk
120 commitsCommits (90d)310 commits
1.2k ★GitHub stars10k ★
10 q'sStack Overflow60 q's
MediumCommunityGrowing
BraintrustLangfuse
Key Differences
| Factor | Braintrust | Langfuse |
|---|---|---|
| License | Proprietary | MIT |
| Language | TypeScript / Python | TypeScript |
| Hosted | Self-hosted | Self-hosted |
| Free tier | — | — |
| Open Source | — | ✓ Yes |
| TypeScript | ✓ | ✓ |
Pick Braintrust if…
- 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
Pick Langfuse if…
- You need full visibility into LLM call traces, costs, and latency
- Running evals and A/B testing different prompts or models
- Self-hosting observability data for compliance or privacy
Side-by-side Quick Start
Braintrust
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 },
});Langfuse
import Langfuse from 'langfuse';
const langfuse = new Langfuse({ secretKey: process.env.LANGFUSE_SECRET_KEY });
const trace = langfuse.trace({ name: 'chat-completion' });
const span = trace.span({ name: 'openai-call' });
// ... make your LLM call ...
span.end({ output: responseText });
await langfuse.flushAsync();Community Verdict
Based on upvoted notes🏆
Langfuse wins this comparison
Trust Score 85 vs 70 · 15-point difference
Langfuse leads on Trust Score with stronger signal data across downloads and community health. That said, the other tool is worth considering if your use case matches its specific strengths above.