Facebook Messenger Seen Locker doesn't let people know you have read their messages.
****IT DOESN'T DISCONNECT YOUR INTERNET****
***Root and BusyBox Required***
How to use:
1-Open FB Messenger Seen Locker
2- Tap Lock
3- Enjoy reading and writing messages without updating your seen stamp
4- Tap Unlock so you can send written messages and receive new ones
Or
1- Open FB Messenger Seen Locker
2- Check Show in status bar
3- Tap to toggle Lock/Unlock in status bar
4- Enjoy!