For years, I’ve been saying how surprising macOS’s Preview app is. Just about everyone knows it is _there_ and lots of people use it to look at pictures and crop and occasionally to annotate. But there’s so much more that Preview can do.

Did you know that you can use Preview to scan and fill out forms using nearby Phones so you can get paper work done and submitted? That’s just one underused feature. It syncs with the phone’s document scanner, to find the outlines of the paper, then performs geometry correction so you can fill out paperwork, whether it’s for your next group hike or your kid’s camp outing. Fill, sign, send, and you’re done.

Preview can also be your new lightweight drawing program, whether you want to work with shapes and text or with freeform lines:

Preview can also adjust photo levels for basic color corrections. The right-hand side is the original. The left shows the picture after I applied auto levels, upped the contrast, and warmed the picture slightly. (Yes, that’s me on the left, and my son on the right in the Powerade reflection.)

I’m not sure who gave the Preview team the go-ahead to add lots of silly and delightful features or whether this is just a dogfood target that somehow got shared with the public, but there’s just so much you can do with it. The other evening, my daughter had begged for a watchkit app and I used Preview to populate my XCAssets for the watch app icon.

If I can get enough people to sign up, I’ll be giving a workshop this week on Preview through Try Swift World, although it’s a bit of a hard sell given how weird a topic it is for an audience of developers.

What’s your favorite hidden app feature that few people know about?