Xcode DerivedData, node_modules and Docker: what’s safe to delete on a developer’s Mac

By Mohit Nippanikar, who makes SiftMac

A developer’s Mac fills up differently. Every project brings its own packages and build output, Xcode keeps build data and simulators for years, and Docker grows one big disk image. Almost all of it comes back with one install or build, which makes it the easiest space to get back, as long as you clear it in projects you’re not working on today.

Step 1: see where it went

This lists the usual suspects with their sizes, biggest last. Folders you don’t have are skipped:

du -sh ~/Library/Developer/Xcode/{DerivedData,Archives,"iOS DeviceSupport"} \
  ~/Library/Developer/CoreSimulator ~/.npm ~/.gradle ~/.cargo ~/.cache/uv \
  ~/Library/Caches/{Homebrew,pip,CocoaPods,Yarn} ~/.android \
  2>/dev/null | sort -h

And every node_modules in your projects folder (change ~/Projects to wherever you keep code):

find ~/Projects -name node_modules -type d -prune -exec du -sh {} + 2>/dev/null | sort -h

Xcode

Clear DerivedData with Xcode quit:

rm -rf ~/Library/Developer/Xcode/DerivedData/*

Simulators belong to Xcode, so remove them the way Xcode does. The first command removes simulators for iOS versions that are no longer installed; the next two list the simulator runtimes, which are several GB each, and delete one you don’t need:

xcrun simctl delete unavailable
xcrun simctl runtime list
xcrun simctl runtime delete <runtime-id>

Runtimes can also be removed in Xcode › Settings › Components (Platforms in older versions).

Node.js: node_modules and package caches

A node_modules folder is everything npm install downloaded for one project, and a few hundred MB each adds up fast across old projects. In any project you’re not working on, it’s safe to delete: npm install (or yarn, pnpm install) brings it back from the lockfile.

To pick them one by one from a list with sizes, run npx npkill in your projects folder. To remove them all in one folder tree without asking, which is only wise for old projects:

find ~/Projects/old -name node_modules -type d -prune -exec rm -rf {} +

The package managers’ own caches are also safe; they download again as needed:

npm cache clean --force
yarn cache clean
pnpm store prune

Python

• Virtual environments (.venv, venv) in old projects: safe to delete when the project has a requirements.txt, pyproject.toml or lockfile to rebuild them from.
• Package caches: pip cache purge, uv cache clean, and conda clean --all for Conda.
• Downloaded models from Hugging Face are often the biggest Python files on a Mac: see What AI tools leave on your Mac.

Docker

Docker Desktop keeps every image, container, volume and build cache inside one disk image, Docker.raw, in ~/Library/Containers/com.docker.docker. Never delete that file. Ask Docker what it can give back, then free it:

docker system df
docker system prune
docker builder prune

docker system prune removes stopped containers, unused networks, dangling images and build cache, and asks first. docker image prune -a also removes images no container uses, which then download again on the next pull. Volumes are left alone unless you add --volumes; they hold databases and other data, so leave them unless you’re sure. Docker.raw is a sparse file: Finder shows its maximum size, du -h shows what it really uses. To cap it, lower the disk limit in Docker Desktop’s Settings › Resources.

Homebrew, Gradle, Android, Rust, Go and CocoaPods

What to keep

• Anything in a project you’re working on now: clearing it only costs you a rebuild.
• Xcode Archives of builds people still run, and Docker volumes.
• ~/.ssh, ~/.gitconfig, ~/.aws, ~/.config and your keychain: keys, settings and logins, tiny and not replaceable.
• Source code without a remote. Check git status and git push before you delete a whole project.