bun.sh/docs/cli/bun-dev.md

In your project folder root (where package.json is):

$ bun bun ./entry-point-1.js ./entry-point-2.jsx
$ bun dev

By default, bun dev will look for any HTML files in the public directory and serve that. For browsers navigating to the page, the .html file extension is optional in the URL, and index.html will automatically rewrite for the directory.

Here are examples of routing from public/ and how they’re matched:

Dev Server URL	File Path
/dir	public/dir/index.html
/	public/index.html
/index	public/index.html
/hi	public/hi.html
/file	public/file.html
/font/Inter.woff2	public/font/Inter.woff2
/hello	public/index.html

If public/index.html exists, it becomes the default page instead of a 404 page, unless that pathname has a file extension.