Back Ext. Counter!

Back Ext. Counter! is a lightweight Chrome extension that counts Back Extensions, estimates active energy for workouts, and saves results to Photos while maintaining a session history. It also supports notifications and optional Apple Health data recording.

Usage is simple: place the iPhone on the floor, tap Start, and keep your face close to the screen (upper part), or count on the iPhone screen. Optional permissions include Apple Health (record data), Tracking (personalized ads), Notifications, and Photo Library access. Available in Japanese and English. Dynamic Island devices are not supported.