How do I load Vim's optional built-in packages like matchit or editorconfig on demand?

Explanation

Vim ships with several useful packages in its opt/ directory that are not loaded by default. The :packadd command loads these optional packages on demand, either interactively or from your vimrc. This gives you extra functionality without third-party plugins — you just need to activate what is already there.

How it works

• :packadd {package} — searches the pack/*/opt/{package} directories in your packpath and sources the package
• The package becomes available immediately — its commands, mappings, and autocommands are loaded
• In your vimrc, use packadd! (with a bang) to add the package to runtimepath without sourcing plugin scripts yet (deferred loading)

Example

Load the built-in matchit plugin to enable extended % matching for HTML tags, if/else blocks, and more:

" In your vimrc:
packadd! matchit

Now pressing % on an HTML <div> tag jumps to its closing </div>, and pressing it on if in many languages jumps to the matching endif or else.

Tips

• Run :echo globpath(&packpath, 'pack/*/opt/*') to list all available optional packages on your system
• Common built-in optional packages: matchit (extended % matching), editorconfig (Vim 9+), comment (Neovim), termdebug (GDB integration)
• Use :packadd termdebug to get a full GDB debugging interface inside Vim without installing anything
• Third-party plugin managers can install plugins into opt/ for lazy loading with :packadd