Built-in /docs endpoint similar to FastAPI for automatic API documentation

[ayushs206]

Feature Request

It would be extremely helpful if Express provided a built-in /docs endpoint (similar to FastAPI) that automatically generates interactive API documentation.

Motivation

Frameworks like FastAPI provide automatic OpenAPI/Swagger documentation at /docs by default. This significantly improves:

• Developer experience
• Faster API testing
• Quick onboarding for contributors
• Reduced dependency on external tools like Postman for small APIs

Currently in Express, developers need to manually integrate third-party packages such as:

• swagger-ui-express
• swagger-jsdoc
• Redoc

While these solutions work well, having an optional built-in documentation middleware would make Express even more developer-friendly, especially for small projects, prototypes, and teaching environments.

Proposed Solution

Provide an optional built-in middleware that:

• Auto-detects registered routes
• Generates OpenAPI schema automatically
• Serves interactive documentation at /docs
• Can be enabled with something like:

app.enableDocs();

[ayushs206]

I would love to raise a PR and contribute to this

[krzysdz]

This is a repeating request (#5192, #4134, #1761, #6481, #3308), but probably not something that will get integrated into Express. There is middleware which can already do this (e.g. https://github.com/wesleytodd/express-openapi), but due to changes in path-to-regexp@8 some things depending on internals broke in Express 5. When pillarjs/router#174 gets merged, then it should solve most of these problems.