Build Output API (v3)

The Build Output API is a file-system-based specification for a directory structure that can produce a Vercel deployment.

Framework authors can take advantage of framework-defined infrastructure by implementing this directory structure as the output of their build command. This allows the framework to define and use all of the Vercel platform features.

The Build Output API closely maps to the Vercel product features in a logical and understandable format.

It is primarily targeted toward authors of web frameworks who would like to utilize all of the Vercel platform features, such as Serverless Functions, Edge Functions, Routing, Caching, etc.

If you are a framework author looking to integrate with Vercel, you can use this reference as a way to understand which files the framework should emit to the .vercel/output directory.

If you are not using a framework and would like to still take advantage of any of the features that those frameworks provide, you can create the .vercel/output directory and populate it according to this specification yourself.

You can find complete examples of Build Output API directories in vercel/examples.

Check out our blog post on using the Build Output API to build your own framework with Vercel.

Native Dependencies: Please keep in mind that when building locally, your build tools will compile native dependencies targeting your machine’s architecture. This will not necessarily match what runs in production on Vercel.

For projects that depend on native binaries, you should build on a host machine running Linux with a x64 CPU architecture, ideally the same as the platform Build Image.

Versions one and two of the Build Output API (formally named File System API) are deprecated and should not be used for new projects. Their documentation is still available for reference purposes:

• File System API (v1)
• File System API (v2)