Wallzup

You spend a long time staring at your smartphone screen, so don’t settle for a backdrop image that’s staid and dull. The app lets you design your own home and lock screens, with images.You can have pictures change automatically, if you want, and there’s a simple "My Collections" feature to keep track of your favorites too. It’s a decent app that has definitely gotten better over the course of the last year. It’s also completely free.