Braintrust vs W&B Weave
A side-by-side comparison of Braintrust and W&B Weave, drawn from Ignaite's continuously-verified listings.
Compared from listings verified as of
At a glance
| Attribute | Braintrust | W&B Weave |
|---|---|---|
| Category (differs) | Eval | Observability |
| Pricing | FREEMIUM | FREEMIUM |
| License (differs) | Proprietary | Open core |
| Deployment (differs) | Cloud | Hybrid |
| Platforms (differs) | Web, API | API, Web |
| Model support | BYO key / model | BYO key / model |
| Vendor (differs) | Braintrust | Weights & Biases |
The honest brief
Braintrust
Eval-first: prompts are versioned objects and CI scorers block a merge when quality regresses.
- Eval workflow as the primary interface
- CI scorers block merges on regression
- Dataset versioning + OTel tracing
- Generous free tier
- Closed-source SaaS
- Self-hosting needs Enterprise contract
- Overkill for tiny single-file eval needs
W&B Weave
One @weave.op decorator handles both tracing and evaluation, tied into the mature W&B experiment-tracking platform.
- Single decorator traces every call
- Tracing + evaluation in one SDK
- LLM-as-judge and custom scorers
- Apache-2.0 SDK
- Ties into W&B experiment tracking
- Traces land in W&B hosted platform
- Best value if already on W&B
- Free only for solo use