A free program for Android, by DoMobile Lab.

With the new AppLock Lite, you can find a new security tool that’s not only handy and free, but also much easier to use than ever before. With an intuitive interface that lets you lock almost every screen, your smartphone will be secure in a second.

With this lightweight app, you can:

Use Pattern or Password locks to quickly, securely unlock your device Password-only lock screen, with no need for a pattern or PINSecure & Lock your device when you’re away with a temporary passcode and PINLock for the apps you use the most, even if the app is installed on other devices Secure Lock your phone on the lock screen, so you can make it unusable while you’re using other apps or a different phone Secure Unlock your phone when you get it back from you. 

With these basic options, you’ll have to get by in just a few seconds.

And, the best part? AppLock Lite is completely free.