CairnOS

Cairn is a companion app for MeshCore LoRa mesh radios. Pair your radio over Bluetooth or WiFi and send messages through a community-built network of radios and repeaters, with no cell service, no internet and no account.

MESSAGING
- Direct messages, channels and room servers in one inbox, with filters
- Public, private and hashtag channels; share or join a channel by QR code
- Delivery status, with retry for failed sends
- Emoji reactions, @mentions, forwarding, search and text selection
- Path details for each message: every hop on a list and a map
- On-device translation of incoming messages
- Chats kept on a Cairn touch radio come over to the app when you pair
- Block contacts or channel senders, filter keywords and mute conversations
- Optional link previews, with a warning for known malware links

DASHBOARD
- Battery, network, radio, GPS, contacts and chats at a glance
- Sunrise and sunset for your position and the radio's temperature sensor
- Radio presets by region, or set frequency, bandwidth, spreading factor, coding rate and TX power yourself

NODES & REPEATERS
- Saved and heard nodes, with search, sort, filters and a card or list layout
- A page for every node, with a map, readings and quick actions
- Log in to your repeaters and room servers to see status, telemetry, neighbors and an SNR map, then change settings, access lists and regions or use the remote CLI
- Send commands to your own companion radios over the mesh (MeshCore 1.18 firmware)
- Telemetry history charts kept on your phone
- Contact groups, QR sharing and a manual path editor

SPECTRUM
- Live noise floor and packet traffic on your frequency
- Signal margin, airtime share and packets per minute
- With a Cairn radio: the radio's own Channel view, with its trace, density heat map and 24-hour noise floor

MAPS & GPS
- Mesh map with standard, satellite and topographic layers
- Live traffic layer: the links packets crossed lately, and each new packet as it arrives
- Download map regions for offline use
- Radio and phone GPS side by side, with a compass and a navigation HUD that points the way to any node

TOOLS
- Network Health, Scan for Nodes, Trace Path, Line of Sight with terrain and Fresnel zone, RX Log and a CLI terminal
- Sign and verify messages with your radio's identity

IN THE CAR & AROUND iOS
- CarPlay: a dashboard of your radio, mesh, messages and location, a GPS page, and messages you hear and answer with Siri
- Siri and Shortcuts: check radio status, send a message or send an advert
- Live Activity and Dynamic Island with connection, battery and unread count
- Multiple windows on iPad

MAKE IT YOURS
- Choose a color, gradient or photo background with glass cards over it
- Give any node a photo or a color: its type's color, one of twelve shades or any color you pick
- Backup and restore, plus CSV and GPX export

PRIVACY
Your messages travel radio to radio. Cairn has no accounts, no analytics and no developer server. Nothing is sent to the developer.

REQUIREMENTS
Requires a LoRa radio running MeshCore companion firmware, connected over Bluetooth or WiFi. Maps, link previews and Line of Sight elevation use the internet when it is available. Requires iOS 18 or later.

Cairn is free and open source software under the GNU GPL v3, built on the work of the open-source MeshCore app community. Source code is linked from our support page.