Brevent, black prevent, can app-standby (since Android 6.0, not supported on some devices) or force-stop apps without root, prevent apps from running in long time.

Brevent never brevent apps not in Bervent list. If apps are launched then quit (tapping Back or so), Brevent will app-standby them; if apps timed out in standby, or swiped from recents screen, Brevent will force-stop them. Whenever apps are running without activity, Brevent will force-stop them.

Apps in Brevent list can be set "allow sync" to receive notifications or do sync jobs. Brevent won't standby "allow sync" apps, and Brevent won't force-stop "allow sync" apps with notifications or running in background.

Brevent supports Android 5.0 to 8.1, requires "USB debugging" in "developer options".

Since Android 8, Brevent won't work if debugging is off or USB option is changed. If debugging turns off when you unplug the cable, please change USB option. Normally, it's OK to keep USB option as default.
From version Brevent 3.2.5.7:
v3.2.5.1 (2018/05/16)
- simplify brevent method, standby (skippable) then force-stop (skippable)
- fix crash on android p dp2
- fix icon for "instant apps"
- rewrite app ops, drop permission GET_APP_OPS_STATS
- fix out of brevent if set no-aggressive
- other little optimization

Don't turn off USB Debugging or change USB options on Android 8+.
Be careful to brevent system apps, core apps or frequently-used apps.
All versions
May 21, 2018
May 16, 2018
May 13, 2018
May 8, 2018
May 1, 2018
April 28, 2018
April 2, 2018
March 18, 2018
March 8, 2018
March 6, 2018