DATA COMMUNICATIONS ANYWHERE
Mercury is a fully open-source HF modem — built for emergency communications, remote communities, and amateur radio operators. Developed by Rhizomatica as part of the HERMES Project
- ⭐150+ GitHub Stars
- 🔱GPL-3.0 Open Source
- 📡HF Radio Compliant
- 🪟Linux & Windows
- 🔁16+ Releases
- 🤝VARA Compatible
Help Us Keep Mercury Free Forever
Mercury is developed by Rhizomatica, a non-profit organization dedicated to connecting remote and underserved communities through open-source telecommunications.
Your support makes a difference
- GPL-3.0 Licensed
- No Vendor Lock-In
- Community Driven
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Mercury delivers high-quality HF data communications in a lean, open-source package.
Adaptive ARQ Protocol
Intelligent error-correction with connect/accept handshake, ACK/retry logic, keepalive, and controlled disconnect. Every byte delivered, even under harsh conditions.
ReliabilityIntelligent Gear-Shifting
Per-direction adaptive mode selection: automatically shifts between DATAC4, DATAC3, and DATAC1 based on live SNR feedback.
PerformanceBroadcast Mode
Simultaneously send data to many stations in parallel alongside ARQ sessions. Dedicated broadcast framing with its own TCP ingress port — one transmitter, many receivers.
ScaleVARA TCP Compatible
Drop-in replacement for VARA TNC. The same control and data socket interface means Mercury works instantly with Winlink, JS8Call, and most ham radio apps.
CompatibilityCross-Platform
Native binaries for Linux (AMD64 & ARM64 / Raspberry Pi) and Windows. ALSA, PulseAudio, WASAPI audio backends. Works on any hardware with a sound card.
PortabilityRadio Agnostic
Works with virtually any amateur or commercial HF radio via Hamlib — Icom, Yaesu, Kenwood, and more. Automatic PTT keying.
FlexibilityFreeDV Physical Layer
Built on field-proven FreeDV digital data modes Mode pool eliminates codec re-initialization — the fastest possible link setup.
Proven TechGPL-3.0 Open Source
Full source code published. No license fees. Audit every line, fork it, extend it, deploy it. Community-driven development.
FreedomUp and Running in Three Steps
Mercury is designed for simplicity without sacrificing usability or performance.
Connect Your HF Radio
Plug your HF transceiver into your computer via a sound card interface (SignaLink, Rigblaster, or built-in). Mercury supports any radio Hamlib does — thousands of models from Icom, Yaesu, Kenwood, and more.
Install & Configure Mercury
Install Mercury via Debian package, compile from source, or download the Windows ZIP. Edit a simple INI config file to set your callsign, audio devices, and radio model. That's it.
Start Communicating
Mercury exposes a VARA-compatible TCP interface. Connect Winlink Express, JS8Call, or any ARQ-capable app. Or use Mercury directly to send files, email, and data thousands of kilometers.
Ready to connect? Follow our detailed installation guide.
View Installation GuideTrusted by World-Class Experts
"I am very pleased to see Rhizomatica using the FreeDV data modes combined with their own custom ARQ protocol to send data over low SNR HF channels. It is great to see Rhizomatica embracing those waveforms, and spreading the use of open source in HF Data."
"Not only has Rhizomatica developed a fully open-source software modem, they have done so to empower communities in need of their own communication infrastructure. We are proud to have supported Rhizomatica in this work, and very excited to see it now available to the amateur community and others around the world using HF for critical communication."
"This development is a very big deal in the evolution of data communications in Amateur Radio. Mercury now offers a well-engineered data communications system for use on the Amateur Radio HF bands...But the real significance of Mercury is that it’s an open source project, and has already been ported to Linux. Prior to Mercury, open source data communications systems for HF were generally lower performance, and not very robust, such as 300 bps Audio Frequency Shift Keying (AFSK) packet radio...I applaud the Mercury developers for their savvy choice to implement the Orthogonal Frequency Division Multiplexing (OFDM) subsystem that was developed and proven out by FreeDV...I hope… expect… that Mercury will eventually become the primary data communications mode in use on Amateur Radio HF."
Built for Humanity, Not for Profit
Rhizomatica is a non-profit. Mercury is a public good. Communication is a human right — and that means the tools must be open, free, and impossible to monopolize.
No Vendor Lock-In
GPL-3.0 means you own your communication stack. Deploy it, modify it, share it. No subscription necessary.
Full Auditability
Every line of code is public. Security researchers, governments, and communities can verify exactly what Mercury does.
Community Driven
Built by Rhizomatica with contributions from radio enthusiasts, researchers, and humanitarian workers worldwide. You can contribute too. Generously supported by ARDC over the years.
Built for Longevity
Open standards (FreeDV, Hamlib) ensure Mercury works today and tomorrow.
Mercury is licensed under the GNU General Public License v3.0. This guarantees your freedom to study, share, and modify the software — and ensures those freedoms are preserved for everyone.
Read the licenseMercury development was sponsored by ARDC — a foundation dedicated to supporting open, digital radio communications.
Install Mercury in Minutes
Choose your platform and follow the steps. Full documentation available at rhizomatica.github.io/mercury.
Join our Community
Join our community mailing list to contribute, report issues, and shape the future of HF communications.