Open-source alternatives to Weights & Biases

4 free, open-source alternatives with 37.5K total GitHub stars. The best open-source alternative to Weights & Biases is Langfuse, with 28.4K GitHub stars.

Updated July 2026Stats synced from GitHub

Compare Weights & Biases alternatives

ToolStarsForksLicenseSelf-hosted
Langfuse28.4K2.9KMITYes
Helicone5.8K592Apache-2.0Yes
Laminar3K203Apache-2.0Yes
mlop38010Apache-2.0Yes

Weights & Biases (W&B) is a widely used MLOps platform for tracking machine learning experiments, hyperparameter sweeps, and model artifacts. It's closed-source and cloud-hosted by default — the free tier is generous for individuals, but team usage and self-hosted deployments require paid enterprise plans, and your experiment data is stored on W&B's servers unless you pay for that option.

mlop is the most direct alternative since it specifically offers a W&B-compatible API, making migration low-friction if you're already using W&B's SDK. Langfuse and Helicone are worth considering instead if your actual need is tracing and observability for LLM applications rather than classic ML experiment tracking, and Laminar if agent evaluation is your primary use case.

FAQ

Is there a free, open-source alternative to Weights & Biases?

Yes. mlop, Langfuse, and Helicone are all open source and free to self-host.

What's the best open-source alternative to Weights & Biases?

mlop is the closest match since it mirrors W&B's API, easing migration. Langfuse is the better pick if you're tracking LLM application behavior rather than traditional model training runs.

What are the top open-source alternatives to Weights & Biases?

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