This NodeBB plugin allows posters to search for an insert gifs from Giphy right in the composer.
It works just like mentions, except you use an ampersand (&) and start typing a word or phrase that you want to search for.
Click on one, and the image is automatically embedded into the post.
If you start running into rate limits, i.e. you're a high-traffic forum and some requests aren't completing, you may need to get your own API key.
Search for "giphy" in the Nodebb Plugins list, or
npm install nodebb-plugin-giphy