Promptfoo is freemium — a usable free tier with paid plans above it. W&B Weave is freemium — a usable free tier with paid plans above it. Both are listed under LLM Eval & Observability, so this is a like-for-like comparison. Neither is ranked above the other — Flocci carries no sponsored placement.
Promptfoo is freemium — a usable free tier with paid plans above it and is listed for open-source CLI/library for evaluating prompts, models and RAG pipelines side by side, runs in CI. W&B Weave is freemium — a usable free tier with paid plans above it and is listed for agent-native tracing model with sessions, steps, tools and sub-agents as first-class concepts (not generic spans). Both sit in LLM Eval & Observability.
Neither — Promptfoo and W&B Weave are both freemium, so the choice comes down to capability rather than cost. Both entries list what they uniquely do above.
Choose Promptfoo if you need open-source CLI/library for evaluating prompts, models and RAG pipelines side by side, runs in CI; choose W&B Weave if you need agent-native tracing model with sessions, steps, tools and sub-agents as first-class concepts (not generic spans). Flocci AI Tools does not rank one above the other — it shows both feature sets side by side and lets the requirement decide.
| Promptfoo | W&B Weave | |
|---|---|---|
| Pricing tier | Free tier + paid plans | Free tier + paid plans |
| Free to start | Yes | Yes |
| Category | AI Models & Local Execution | AI Models & Local Execution |
| Type | LLM Eval & Observability | LLM Eval & Observability |
| Listed capabilities |
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| Tags | promptfoo, prompt testing, llm red teaming, eval framework, open source, free, ci for prompts | weights and biases weave, agent observability, llm tracing, evaluation framework, free tier |
| Website | promptfoo.dev | wandb.ai |
| Full page | Promptfoo details → | W&B Weave details → |
| Alternatives | Promptfoo alternatives → | W&B Weave alternatives → |