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W&B Weave vs Langfuse
Quick verdict
W&B Weave and Langfuse are closely matched on licensing, self-hosting and OpenTelemetry support — the decision comes down to pricing and framework integrations below.
Side-by-side comparison from the Agent Observability Index: licensing, self-hosting, pricing model and integrations — no vendor copy, primary sources linked.
| W&B Weave | Langfuse | |
|---|---|---|
| One-liner | LLM tracing and evaluation toolkit from Weights & Biases, integrated with the broader W&B experiment-tracking ecosystem. | Open-source (MIT) LLM engineering platform combining tracing, prompt management, evals and datasets, widely used as the default self-hosted observability stack. |
| Category | Observability & Tracing | Observability & Tracing |
| OpenTelemetry-native | Yes | Yes |
| Open source | Yes | Yes |
| Self-hostable | Yes | Yes |
| Pricing model | freemium | freemium |
| Pricing notes | Free tier on W&B cloud; usage-based ingestion pricing; enterprise self-hosting via W&B Server | Free Hobby tier (50k units/mo); Core $29/mo, Pro $199/mo, unlimited users on paid tiers; MIT core fully self-hostable |
| Frameworks | openai-sdk, anthropic, langchain, llamaindex, mistral | langchain, openai-sdk, llamaindex, litellm, opentelemetry, vercel-ai, haystack |
| GitHub stars | 1.1k | 29k |
| Maturity (GitHub signal) | 87/100 (Mature) | 90/100 (Mature) |
| Funding / ownership | Weights & Biases acquired by CoreWeave (~$1.7B, 2025) | YC W23; $4M seed (Lightspeed, La Famiglia) |
How to choose
- Both link to primary pricing sources below — verify current tiers before committing; this market shifts monthly.
Frequently asked questions
Is W&B Weave or Langfuse open source?
W&B Weave: Yes. Langfuse: Yes.
Can W&B Weave and Langfuse be self-hosted?
W&B Weave: Yes. Langfuse: Yes.
W&B Weave vs Langfuse: which should I choose?
W&B Weave and Langfuse are closely matched on licensing, self-hosting and OpenTelemetry support — the decision comes down to pricing and framework integrations below.