Work.

A bubble level, a real ruler and a protractor, calibrated to the phone in your hand.

A metronome you can dial or tap, and a chromatic tuner that turns green when you are in tune.

HIIT, Tabata, Pomodoro and custom rounds, with a session screen you can read from across the room.

Uses your phone's magnetometer to find iron and steel: the screws in a stud, a nail in a beam, a buried pipe clip.

Pushes water out of your phone's speaker grille, tests each speaker, and plays tones from 1 Hz to 22 kHz.

Lost your phone under a cushion? Clap or whistle and it rings, even on silent.

A compass that always tells you which north it is showing, with bearing hold, calibration help and the Qibla direction.

Startle sounds an alarm when the phone is moved, taken from a pocket or unplugged. Arm it before you leave your phone on a café table or charging in a shared room.

A tally counter for laps, reps, visitors and pages, with presets for tasbih, dhikr and japa.

A reverse singing challenge and voice changer, with sound effects made on your phone.

Spin the wheel to decide: custom wheels, a name picker, a coin flip and a finger chooser for who goes first.

A guided phone checkup in about 3 to 5 minutes, then a plain pass/fail report you can share.

A dice roller for board games, game nights and tabletop RPGs. Tap the tray and two six-sided dice roll at once, with the total in large numbers.