TonTsu

Send messages with light and sound where there's no signal. One-tap SOS, point the camera to decode blinking lights into text. Works fully offline.

TonTsu is a Morse code communication app that works where there's no signal — camping, hiking, festivals, emergency preparedness, or just secret messages with friends.

■ Send with light

• Your message becomes flashlight blinks in Morse code
• One-tap SOS that repeats until you stop it
• Kana and kanji are romanized automatically; Japanese Wabun code supported
• Save frequent messages as presets for one-tap sending

■ Read light

• The camera decodes blinking lights into text in real time
• A thermal-style view makes light sources pop
• International / Wabun auto-detection, with kana readings for romaji
• 1×/2×/5× zoom catches distant lights

■ Morse by sound (Pro)

• Generate Morse audio from text and play it back
• Save and share as an audio file (m4a)
• Decode Morse tones around you with the microphone — any pitch works

■ Learn the code

• Charts for A–Z, Japanese kana, and numbers & symbols
• Tap any character to hear its rhythm
• Three sending speeds: slow, normal, fast

■ Fully offline Everything happens on your device. No account, no data collection, no network.

TonTsu Pro (one-time purchase)

• Morse by sound (generate / save / share / mic decoding)
• Color themes (night-vision red & green, and more)
• Preset limit raised from 1 to 20

Note:

• This app is not a substitute for official emergency services.
• Contains flashing-light effects. Take care if you are sensitive to flashing lights.