ContactMonkey's template builder allows you to easily embed GIFs in your email templates using the Giphy library. All GIFs uploaded from here are fully compatible and will animate in the template once inserted.
You may also use the file manager to upload custom GIFs as an image (insert image content block > browse > upload > insert). Sometimes, these GIFs may not appear animated once inserted into ContactMonkey's template builder, which requires some additional work to be done by the user:
1. Visit https://gifyu.com/
2. Drag in the desired GIF and click upload to generate your GIF URL.
3. Right-click the GIF and click "copy image address".
4. Paste the URL into the URL field within the content properties section (as seen below).