TeslaUnread provides unread count badges for Nova Launcher Prime and WidgetLocker. It will not work with other desktops or lockscreens.
Unread counts are natively supported for the most popular chat and email apps, such as Hangouts, Whatsapp and all the apps shown in the screenshot.
Additionally on Android 4.3+ TeslaUnread can watch the notification bar to extract unread counts from virtually any app.
5.0beta3 Feb 19, 2016
Fix unable to disable some apps
Fix exchange/pop counts for latest Gmail update
size: 1.28 MB
version: 5.0beta3 (40104)
Min: Android 4.4 (Kitkat, API 19)
Target: Android 6.0 (Marshmallow, API 23)