Proof! is one of the apps that myself and the amazing Mindbloom team built a couple of years ago. It's a fun way to create challenges for you and your friends. Once you accept a challenge, you must keep adding "proofs" (video or photo) that you did whatever you were supposed to do!
I've started a new challenge - "Tweet 1 cat photo per day". Feel free to add me on Facebook and join us here: https://proof.mindbloom.com/proo...
Disclaimer: although me and my previous team built the app, it's not maintained anymore, so sorry if you find any bugs or have any issues :(
Wellfound