How to add a Homebrew tap

Homebrew taps are additional Git repositories that provide formulae, casks, or external Homebrew commands outside the package sources already known to the active prefix. Adding a tap is common when a project publishes its own package source or when a vendor keeps packages separate from homebrew/core and homebrew/cask.

The short tap form uses user/repo and assumes a GitHub repository named user/homebrew-repo. A project can also provide a full Git URL for taps hosted elsewhere, but the visible Homebrew tap name remains the value that later appears in brew tap and fully qualified package names.

Non-official taps can contain Ruby package definitions and external commands that Homebrew may load during package operations. Homebrew 6 separates adding a tap from trusting its contents, so inspect the tap after cloning it and trust only the specific formula, cask, or command needed for short-name installs unless the entire tap is under your control.

Steps to add a Homebrew tap:

Confirm the tap name from the project or vendor documentation.

For GitHub taps, symfony-cli/tap maps to the repository named symfony-cli/homebrew-tap. For a custom Git remote, use the full URL supplied by the project as the second argument to brew tap.
Add the tap to Homebrew.
```
$ brew tap symfony-cli/tap
==> Tapping symfony-cli/tap
Cloning into '/opt/homebrew/Library/Taps/symfony-cli/homebrew-tap'...
Tapped 1 formula (13 files, 140.7KB).
```
Replace symfony-cli/tap with the tap named by the package documentation. On Linux or WSL, the clone path usually starts with /home/linuxbrew/.linuxbrew instead of /opt/homebrew.
List installed taps and confirm the new tap appears.
```
$ brew tap
homebrew/core
symfony-cli/tap
```
Inspect the tap details and trust state.
```
$ brew tap-info symfony-cli/tap
symfony-cli/tap: Installed
Untrusted
1 formula
/opt/homebrew/Library/Taps/symfony-cli/homebrew-tap (13 files, 140.7KB)
From: https://github.com/symfony-cli/homebrew-tap
==> Formulae
symfony-cli
```
Untrusted means Homebrew has not been told to load non-official package code from this tap for short-name operations. Trust only taps or packages that you would allow to run Ruby code with your user permissions.

Check a package from the tap by fully qualified name.

$ brew info symfony-cli/tap/symfony-cli
==> symfony-cli/tap/symfony-cli: stable 5.17.1
Symfony CLI helps Symfony developers manage projects, from local code to remote infrastructure
https://symfony.com
Not installed
From: https://github.com/symfony-cli/homebrew-tap/blob/HEAD/Formula/symfony-cli.rb
Tap: symfony-cli/tap

A fully qualified name keeps the lookup tied to the tapped repository, which matters when another tap or homebrew/core has a similar token.
Related: How to check Homebrew package information

Trust the specific tapped formula when short-name installs are required.
```
$ brew trust --formula symfony-cli/tap/symfony-cli
Trusted formula: symfony-cli/tap/symfony-cli
```
For casks, use brew trust --cask user/repo/cask. Trusting user/repo without --formula or --cask trusts the whole tap, including future package definitions.
List trusted entries before installing by short name.
```
$ brew trust
All official taps and commands are trusted.
Trusted formulae:
  symfony-cli/tap/symfony-cli
```
After this check, install with brew install symfony-cli/tap/symfony-cli to stay fully qualified, or brew install symfony-cli only when the specific formula is trusted.
Related: How to install a Homebrew formula