And433

An Android app for decoding 433 MHz RF signals natively using an RTL-SDR dongle connected via USB OTG.

And433 uses rtl_433 compiled directly into the app via Android NDK and FFI — no external server or network connection required to decode signals.

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Features

• Native RTL-SDR support — connects directly to an RTL-SDR dongle over USB OTG using a patched librtlsdr (rtl_tcp_andro)
• Full rtl_433 decoder — all 200+ device protocols supported out of the box
• GPS tagging — each decoded packet is tagged with the device's GPS coordinates at the time of capture
• Search & filter — live search across all packet fields; filter by device model using chips
• Adjustable gain — slider from 0 dB (hardware AGC) to 49.6 dB; defaults to 40 dB
• Bias-T support — optional 5V supply on the antenna port (RTL-SDR Blog V3/V4)
• Export captures in two formats:
  • .a433 — JSONL format with session header and GPS-tagged packets (see below)
  • .kml — Google Earth / Maps compatible, one placemark per GPS-tagged packet
• Share data with 433map.com — automatic upload of new packets while decoding

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Requirements

• Android 6.0+ (API 23), arm64
• RTL-SDR dongle (RTL2832U-based)
• USB OTG cable or adapter

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Building

# Clone with submodule dependencies
git clone https://github.com/SarahRoseLives/and433.git
cd and433

# Build the Flutter app (NDK 27 required)
cd and433_app
flutter run

The NDK build compiles libusb, librtlsdr, and rtl_433 into a single librtl433_ffi.so via the CMakeLists in rtl_433/android/.

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Capture Format (.a433)

And433 uses a simple JSONL (JSON Lines) format with the .a433 extension.

Line 1 — session header:

{"_a433":"1.0","_created":"2026-04-01T00:00:00.000Z","_freq_hz":433920000}

Lines 2+ — one decoded packet per line, all rtl_433 fields plus injected GPS fields:

{"time":"2026-04-01 00:01:23","model":"Acurite-Tower","id":12345,"temperature_C":21.4,"humidity":58,"_lat":51.5074,"_lon":-0.1278,"_gps_accuracy":4.2,"_gps_time":"2026-04-01T00:01:23.000Z"}

GPS fields (_lat, _lon, _gps_accuracy, _gps_time) are present when the device had a GPS fix at the time of capture. Packets without a fix omit these fields.

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433map.com

And433 can automatically share your captures with 433map.com, a community map that plots GPS-tagged RF sensor data contributed by users worldwide.

How it works

1. Log in to your 433map.com account via Export → Upload to 433map.com in the app
2. Once authenticated, new packets are uploaded automatically every 30 seconds while decoding
3. A cloud icon in the toolbar shows the current upload state
4. Your token is stored securely on-device — you only need to log in once

API

The app communicates with two endpoints:

Method	Endpoint	Description
POST	/api/auth/login	Authenticate with {"username":"…","password":"…"}, returns {"token":"…"}
POST	/api/ingest	Upload .a433 JSONL body with Authorization: Bearer <token> header

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Architecture

Flutter UI (Dart)
    │
    │  dart:ffi
    ▼
librtl433_ffi.so  (Android NDK / C)
    ├── rtl_433         — decodes IQ samples → JSON packets
    ├── librtlsdr       — patched for Android fd-based open (rtlsdr_open2)
    └── libusb          — patched for Android (no enumeration, fd-only)
    │
    │  UsbManager (Java/Kotlin)
    ▼
RTL-SDR dongle  (USB OTG)

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License

GNU General Public License v2.0 — the same license as rtl_433.
See COPYING for the full license text.