We're releasing Skipped Builds as a new experimental feature that skips the build step when the same source code was already built in a previous deployment.

Here's what that looks like with PR environments:

1. You open a Pull Request, and Railway builds it in a PR environment.
2. You merge your Pull Request. The merged commit is identical to what was already built.
3. Railway detects that the same code was already built, and deploys your app instantly.

No time spent cloning your repo, installing dependencies, or running build steps.

🚀 How to enable skipped builds

Skipped Builds is disabled by default right now, and can be enabled per service. You can enable it under Feature Flags in your Service Settings.

💡 Note on environment variables

One thing to keep in mind: we only compare source code to decide whether to skip a build, not environment variables. If your build inlines environment variables (like NEXT_PUBLIC_* in Next.js or VITE_* in Vite), the cached image will still contain the values from the original build. Check out the Skipped Builds Docs for details on how to handle this.

💬 Any Feedback?

We'd love to hear how this works for you. Let us know if you run into anything!