PacketChess - Chess Over Packet Radio

The Idea

What if you could play chess over the air? PacketChess brings turn-based chess to amateur radio using AX.25 packet communication.

Each move is just a few dozen bytes. Invite an opponent by callsign, choose your color, and play a full game of chess over VHF or HF.

Whether you're on a local repeater frequency or reaching across continents on HF, PacketChess turns idle radio time into a competitive match.

                            ♔
                            Full chess rules
                        

                            📡
                            Works over radio
                        

                            💬
                            In-game chat
                        

Features

📡

Over the Air

Moves are transmitted as compact AX.25 packets.

🔁

Reliable Delivery

Automatic acknowledgment tracking with manual retry. Never lose a move to a missed packet.

💻

iOS & macOS

Native apps for iPhone, iPad, and Mac. Play on the go with a handheld or from your home station.

See It In Action

iPhone

PacketChess games list showing active and past games — Games list

PacketChess board with move highlighting — Move highlighting

PacketChess showing check detection — Check detection

macOS

PacketChess macOS check detection — Check detection

PacketChess macOS checkmate screen — Checkmate

How It Works

1

Invite

Enter your opponent's callsign and choose your color. The invitation is sent over the air.

→

2

Accept

Your opponent sees the invitation and accepts. The game begins.

→

3

Play

Take turns making moves. Each move is transmitted as a compact FEN packet over radio.

→

4

Checkmate

The game ends with checkmate, stalemate, draw, or resignation. Start another round!

Three Ways to Connect

Software TNC

PacketChess processes audio directly. Use an audio cable or Digirig for your radio connection.

Bluetooth TNC

Connect wirelessly via Mobilinkd TNC3 or TNC4. No cables between your device and radio.

Network TNC

Connect to Direwolf or other KISS TCP servers on your network for home station setups.

Technical Specifications

Protocol AX.25 v2.0 compliant

VHF/UHF Speed 1200 baud AFSK

HF Speed 300 baud FSK

Error Correction FX.25 Reed-Solomon

Compression Zlib

Supports TNCs KISS protocol

Platforms iOS 17+, macOS 15+

Move Encoding FEN

Suggested Frequencies

2m 145.070 MHz FM

80m 3.587 MHz USB

40m 7.065 MHz USB

30m 10.143 MHz USB

20m 14.093 MHz USB

VHF: 1200 baud AFSK FM · HF: 300 baud AFSK USB

Getting Started

What You Need

✓ iPhone, iPad, or Mac (iOS/iPadOS 17.6+, macOS 15.6+)
✓ A ham radio (VHF/UHF HT or mobile, or HF transceiver)
✓ Audio cable + Digirig (or VOX cable), Bluetooth TNC (Mobilinkd), or Network TNC
✓ Valid amateur radio license
✓ An opponent

PacketChess uses the same TNC engine as PacketMessage. If you already have PacketMessage set up, you're ready to play. Just use the same radio and cable setup.

Support PacketChess

PacketChess is built by a solo ham radio operator as an after-hours passion project. You can support development through the in-app Tip Jar, or via PayPal below.

Thank you! Every contribution makes a difference.