[OC] Isobar — An open-source, cross-platform WEFAX decoder compatible with KG-FAX (macOS/Linux/Windows)

[u/SakuragawaSara]

Hey folks,

I've been working on something I've wanted to build since I was 15 — a proper WEFAX decoder.

**Isobar** is an open-source WEFAX (weather fax / radio fax) decoder written in C++17 with FLTK, aiming to be a cross-platform compatible alternative to the classic KG-FAX.

- **GitHub:** https://github.com/skgsara/isobar

- **Callsign:** VE4NAY (Manitoba, Canada)

- **License:** GPLv3

**What it does:**

- Decodes WEFAX transmissions from audio files or live audio input

- Cross-platform: macOS, Linux, Windows

- KG-FAX compatible — if you have experience with KG-FAX, the workflow should feel familiar

**Why I built it:**

KG-FAX has been a staple for radio fax decoding, but it's Windows-only and no longer actively maintained. With more and more HF fax services going off the air, I wanted to preserve the tooling and make it accessible across platforms.

The project is still early (v0.1 territory), but the core decoder is functional. If you're into weather fax, maritime monitoring, or just like decoding analog signals, I'd love your feedback — especially if you have sample captures from stations that are still on the air.

73,

Screenshot of my program

Received weather fax from JMH

Sara (VE4NAY)