If you're using Mastodon through your server's website on a computer, you can type emoji directly:
1. Type a colon : and without a space start typing a keyword, this opens a popup
2. Select the emoji you want with the arrow keys and press enter
3. If the one you want isn't there, click the 🙂 icon at the bottom of the post-writing box to open the full picker
The keyword results are partly based on alt-text names of emoji. Hover over an emoji in the picker to see its name.
Edited 2d ago