Neptune.ai was a hosted experiment tracking platform for ML teams, with a free tier for small teams and paid plans from $50/user/month. Neptune was acquired by OpenAI in 2026 and is shutting down its SaaS platform in March 2026, which makes migrating to a self-hosted alternative a practical necessity for existing users rather than just a preference.
FAQ
Is there a free, open-source alternative to Neptune.ai?
Yes. mlop is Apache-2.0 licensed, self-hostable, and offers a W&B-compatible API for experiment tracking.
What's the best open-source alternative to Neptune.ai?
mlop is a timely option since it covers experiment tracking and model registry needs similar to Neptune, and doesn't depend on a vendor that's shutting down its platform.
What are the top open-source alternatives to Neptune.ai?
Browse all open-source alternatives to MLflow for more experiment tracking tools, or explore the full Developer Tools category.