Next.js .gitignore template

.next is the build directory and the most important rule here. It holds the compiled server and client bundles, the route manifests, the image optimisation cache and the incremental build trace. It is regenerated by a build and it is large, and because much of it is content hashed, a committed copy produces a diff of thousands of renamed files on every change.

out is the static export directory, produced only when the project exports to plain HTML files. Having both rules means the template covers either output mode without you needing to know which one this project uses. build appears too, for projects that redirect output there.

.env*.local is a single wildcard doing the work of four separate rules. It matches .env.local, .env.development.local, .env.production.local and .env.test.local in one line. The deliberate omission is the same as in the sibling template: a plain .env is not matched, because that file is meant to hold shared non secret defaults that everyone gets from the repository.

.vercel holds deployment linkage: the project and organisation identifiers that connect this checkout to a hosted project. It is created by the deployment tool on your machine and describes your account's relationship to the project, not the project itself. Committing it points every collaborator at the same hosted project, which is occasionally what a team wants and more often an accident nobody notices until a deploy goes somewhere unexpected.

next-env.d.ts is the odd one out, and the guidance has shifted. The file is regenerated on every build, so ignoring it is defensible, but the framework's own scaffolding commits it, because a fresh clone that runs a type check before a build otherwise fails on missing global types. If your CI type checks before building, remove that line.