Questions, answered.

Convenience and good karma. The Play Store build updates itself automatically in the background, installs in one tap with no "allow unknown sources" steps, and is Play Protect verified — which makes it the easy choice for a phone you don't want to fuss with. The purchase also directly funds continued development. The app itself is identical to the free GitHub build.

Yes — a Google Play build is in the works and will land soon, with one-tap install and automatic updates. For now, download the free APK from the GitHub Releases page — it's exactly the same open-source application.

Download the latest .apk from GitHub Releases, tap it, and approve the one-time "install from this source" prompt Android shows. Then open RTTYAF and grant the USB and microphone permissions. Full step-by-step instructions are on the Download page.

Any CAT-capable HF radio that the underlying Hamlib-style control supports — including popular rigs like the Icom IC-7300 and Yaesu FT-891, with rig model, control mode, and audio device pickers in Settings. RTTYAF includes specific fixes such as setting the FT-891 to 3000 Hz bandwidth in DATA-USB mode. If your rig isn't listed, open an issue and let us know.

A single USB connection from your phone to the rig's USB port handles both CAT control and audio on most modern radios. Newer phones connect with a USB-C cable directly; older phones need a USB-OTG adapter. Your device must support USB host (OTG) mode.

Yes. RTTYAF can decode from the phone's microphone, so you can hold it up to a speaker or just explore the interface and watch the waterfall before wiring up CAT control. It's a good way to learn the layout first.

All the standard RTTY sub-bands from 160m through 6m are built in, with one tap to switch. The waterfall covers the full audio passband so you can see and work everything in the segment at once.

RTTYAF is a fork of FT8AF that swaps the digital mode: a pure-Kotlin Baudot/ITA2 RTTY modem for live decode and real FSK transmit, programmable macros, contest-style logging with Cloudlog and QRZ auto-upload, USB CAT rig control, and a Jetpack Compose / Material 3 dark UI. FT8AF is itself a modern fork of FT8CN, so RTTYAF stands on that lineage.

RTTYAF ships with an English interface today. It's built on the same framework as FT8AF (which is localized into several languages), so additional languages can follow — translation pull requests are welcome on GitHub.

It's built by Patrick Burns (K1AF) and Reid (N0RC) — much of it, famously, vibe-coded on I-70 on the way to Hamvention. Huge credit goes to BG7YOZ, the original author of FT8CN, and N0BOY, who hosts the original repository. None of this exists without them.

Please do. The code lives on GitHub — open an issue for bugs or feature ideas, send a pull request, or just star the repo to follow along. Field reports from real on-the-air use are especially welcome.

That's the plan. Development is active and ongoing. The fastest way to get new builds automatically is the Google Play version; otherwise watch the Releases page or the repo. Want a nudge when something ships? Join the update list on the home page.