Using .claudeignore-Style Exclusions to Keep Irrelevant Files Out of Context

Most codebases carry a lot of weight that has nothing to do with the code itself: node_modules, build output, lockfiles, old test fixtures, generated files, stale data directories. None of it is useful context for Claude Code, and all of it is technically discoverable when Claude searches the project. A .claudeignore file is how you tell Claude Code to stop looking there — but it's worth understanding precisely what that does and doesn't cover before you rely on it for anything sensitive.

What .claudeignore actually does

A .claudeignore file lives at your project root and is structured exactly like .gitignore: exact paths, wildcards, trailing slashes for directories, # for comments. Files and directories matching its patterns are excluded from Claude's context when it's exploring and searching the project.