gemoji

Gemoji is a Ruby library made by GitHub that gives your code access to emoji character information. It stores data about each emoji, including its name, any alternate names it goes by, the Unicode character it represents, and the image file used to display it visually.

The main things you can do with it are look up an emoji by its text alias (like "cat") and get back the actual Unicode symbol, or go the other direction and turn a Unicode character into an emoji name. This makes it straightforward to convert text shortcodes like :cat: into the real character or into an image tag for display in a web app.

It also includes tools for adding your own custom emoji to the list. You can register a new emoji with a name, attach alternate names and tags to it, and point it at an image file in your app's asset folder. Existing emoji can be updated the same way, adding new aliases or tags without replacing the entry.

The library ships with a sample Ruby on Rails helper that shows how to scan user-written text for shortcodes and replace them with small images. That pattern is the most common use case, turning plain text like "it's raining :cat:s and :dog:s" into a page that shows the actual emoji images inline.

It is a small, focused library with no complex setup. You add it to a Ruby project's dependency list and it is ready to use.