Braintrust vs Langfuse
Overview
Braintrust is an end-to-end AI product platform trusted by companies like Notion, Stripe, and Vercel. It combines logging, evaluation datasets, prompt management, and an AI proxy with automatic caching and fallback. Braintrust's evaluation framework helps teams measure quality across prompt iterations with customizable scoring functions.
Langfuse is an open-source LLM observability platform that provides tracing, analytics, prompt management, and evaluation for AI applications. It captures detailed traces of LLM calls, supports custom scoring, and integrates with LangChain, LlamaIndex, Vercel AI SDK, and raw API calls. Langfuse can be self-hosted for data privacy or used as a managed cloud service. Its open-source model and generous free tier make it popular with startups and developers.
Key features
Core capabilities each platform advertises.
- Real-time LLM logging and tracing
- Built-in evaluation framework
- Prompt playground
- Dataset management
- Human review workflows
- Open-source LLM observability
- Detailed trace and span tracking
- Prompt management
- Evaluation scoring
- Self-hosted and cloud options
Strengths and tradeoffs
What each tool does well, and the limitations to keep in mind.
Pros
- Custom-built Brainstore database optimized for AI data with fast full-text search and low latency
- Framework agnostic with native SDKs for multiple languages and no vendor lock-in
- Comprehensive security and compliance certifications including SOC 2 Type II, GDPR, and HIPAA
- AI-assisted Loop Agent for automated optimization of prompts and evaluations
- Strong backing with $80M Series B funding and customers including Vercel, Notion, Coursera, and Dropbox
Cons
- Relatively new platform founded in 2022, less mature than some competitors
- Pro plan at $249/month may be expensive for smaller teams or individual developers
- Limited public information about advanced features and customization options
Pros
- Fully open-source with MIT license and free for commercial use with no usage limits
- Acquired by ClickHouse in January 2026, providing strong backing and future investment
- Active development with strong community support and comprehensive documentation
- Transparent pricing model based on units rather than complex metric calculations
- Deep integrations with major frameworks like LangChain, OpenAI, and LlamaIndex
Cons
- Recent acquisition by ClickHouse may lead to platform changes and strategic shifts
- Smaller team of 7 employees may impact support capacity
- Enterprise pricing at $3,450-$5,700/month can be expensive for mid-sized teams
Braintrust or Langfuse — which should you choose?
Choose Braintrust if you wantChoose if you want
- Iterating on prompts with real production data
- Running evaluations across model versions
- Building golden datasets from production traffic
- Human-in-the-loop review of LLM outputs
- Cost and latency optimization
Choose Langfuse if you wantChoose if you want
- Self-hosted LLM monitoring
- Open-source tracing for AI applications
- Prompt versioning and management
- Cost tracking across providers
- Community-driven observability
Compare Braintrust and Langfuse on your own traffic
Respan lets you trace LLM and agent calls across any model or framework, A/B test prompts on production traffic, and route requests across 500+ models through one gateway.