Ringer, developed by BugZero, is a free and ads-free Android app that allows you to personalize your contacts' ringing mode. It is a utility and tool app that helps you to manage your phone's ringing mode and set it based on your preferences for each contact.

With Ringer, you can now go silent in general mode, but still have the option to ring for particular contacts. This app sets the ringing mode based on what you want for a particular contact. If someone's call is very important to you, you can set their contact to ring or vibrate as per your requirement. On the other hand, if you want to ignore someone's call, you can put their call on silent. Therefore, whenever you receive a call, your phone will ring, vibrate, or remain silent based on the settings for that contact.

Overall, Ringer is a useful app that helps you to manage your phone's ringing mode efficiently. It is easy to use and has a simple interface that allows you to personalize your contacts' ringing mode quickly and effectively.