It features lots of effects, frame shapes and patterns, as well as sharing to other applications (Instagram, Facebook, Twitter and email).
What if you want to add a captioned font onto a photo? Over is hands-down the best app for the iPhone (I don’t know the best app for Android users—sorry). It’s fun to use, offers wonderful fonts and lots of ways to share your photos.
If you want to add free caption overlays to photos online, use Google’s Creative Kit, which is baked into Google+. You will need to create a Google account and upload images to Google+.