These apps live inside the Messages app and carry a wealth of extra functionalities, from song sharing to sticker creating. No matter what type of chatter you are, you’re bound to find at least a few that are of interest. To get at them, open an iMessage conversation and tap the gray app store icon to the left of the message box. There you’ll see apps you’ve already added, and you can find more by tapping the blue app store icon.
A simple, well-designed library of super-sized emojis, this tool will help you liven up your conversations with something a little bit different. Almost everyone else is using the standard iMessage emoji set, so this will ensure you stand out. The catalog covers a broad range of emotions, and there are even some animated emojis if you want to make your expressions a little more lively.
ETA is a full-fledged iOS app that also has an iMessage component, and it simply uses a range of stylish buttons to tell your contacts how long it will be before you arrive. The destinations you’ve searched for in the app will appear in iMessage, with your ETA to those spots calculated based on the latest live traffic data sourced through the app.
Source : https://www.popsci.com/diy/imessage-add-ons/