📖 The AI Tool Bible

Langfuse vs Weights & Biases

A side-by-side look at pricing, capabilities, pros, cons, and our editorial scores.

 
Langfuse
Evaluation
Weights & Biases
Evaluation
TaglineOpen-source LLM observability, prompt management, and evaluation in one platform.The ML experiment tracker, now with LLM eval features.
CategoryEvaluationEvaluation
PricingFreemium· Free self-host & Hobby tier; Core $29/mo, Pro $199/mo, Enterprise $2,499/moFreemium· Free personal; team from $50/mo per seat
ModelModel-agnosticPlatform (any LLM)
Editorial score—8.4 / 10
Use cases
llm-observabilityprompt-managementllm-evaluationagent-tracingrag-debugging
ML experimentsLLM evalWeave
Pros
  • Fully open source and self-hostable at no cost
  • Tracing, prompts, and evals in one platform instead of three
  • Built on OpenTelemetry with SDKs for Python and JS
  • Integrates with OpenAI SDK, LangChain, LlamaIndex, and 100+ libraries
  • Generous free Hobby tier with no credit card required
  • Industry-standard for ML tracking
  • Weave adds LLM-native eval
  • Mature, reliable
  • Strong enterprise features
Cons
  • Cloud pricing by 'units' is opaque until you instrument and measure
  • Self-hosting Postgres + ClickHouse stack is non-trivial to operate
  • Pro/Enterprise jump ($29 to $199 to $2,499) leaves a gap for mid-size teams
  • Heavier UX than LLM-native tools
  • LLM features still catching up
Websitelangfuse.comwandb.ai
Pick Langfuse if
  • ✅ Fully open source and self-hostable at no cost
  • ✅ Tracing, prompts, and evals in one platform instead of three
  • ✅ Built on OpenTelemetry with SDKs for Python and JS
  • ✅ Integrates with OpenAI SDK, LangChain, LlamaIndex, and 100+ libraries
Pick Weights & Biases if
  • ✅ Industry-standard for ML tracking
  • ✅ Weave adds LLM-native eval
  • ✅ Mature, reliable
  • ✅ Strong enterprise features
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