Book of Signals

Book of Signals is a focused offline tool for learning and practicing International Morse code.

Create training sets for letters, digits, words, or your own custom content. Adjust playback speed, tone frequency, and spacing, then answer with the keyboard or a dedicated dot-and-dash pad.

Key features:

- Precise locally generated Morse audio
- Letter, digit, word, and custom training modes
- Adjustable WPM, pitch, and signal spacing
- Keyboard and dot-dash answer input
- Plain text to Morse encoding and Morse decoding
- Local session history and per-character mistake statistics
- Search, filtering, sorting, duplication, and autosave
- JSON backup and restore through Android's system file picker
- Light, dark, and system themes

The app works without an account or backend. It contains no ads, subscriptions, analytics, or required internet connection. Your projects, answers, and progress remain on your device unless you explicitly export a backup file.