The npx cache was 2.4 GB of tools run once and never again

npx create-something feels like it runs a tool and leaves nothing behind. It does not. npx installs the package and every one of its dependencies into a folder under ~/.npm/_npx, and that folder is never cleaned up.

Why it grows

• Each distinct package, and each distinct version of it, gets its own folder named by a hash.
• The folder holds a complete node_modules, so a scaffolding tool with a heavy dependency tree costs hundreds of megabytes the first time you run it.
• Nothing expires. A tool you ran once for a tutorial eighteen months ago is still there.

See what is in it

du -sh ~/.npm/_npx/* | sort -h | tail -10

# Which package a folder is for
cat ~/.npm/_npx/<folder>/package.json

Clearing it

Everything in _npx is a copy of something on the registry, so removing it costs one download the next time you run that tool.

rm -rf ~/.npm/_npx

npm cache clean --force does not touch this folder. It empties ~/.npm/_cacache, the download cache, which sits next to it, and that is covered in npm cache taking up space. The two are separate, which is why a Mac can have run the clean command and still carry gigabytes here.

Keeping it small

• For a tool you run weekly, a global install is one copy you can see and update: npm install -g <tool>. The cost of those is in global npm packages.
• For a one-off, npx is still the right call. Clear the folder every few months.
• Project dependencies are a different, larger problem, measured in node_modules taking up space.