Who it's for

Messaging for search and rescue, CERT and ARES teams

Text, photos and exact locations between your volunteers' phones when the cell network is gone, next to the radios you already run.

Your team already has a plan for when the cell network fails, and it runs on radios. Some things are still awkward to pass by voice, like a photo of a clue, coordinates that someone has to read back digit by digit, or a note for a teammate who's out of range right now.

Knit is a free Android app that sends those between phones, with no cell service or internet needed. Phones running Knit connect directly over Bluetooth and Wi-Fi and pass each message along through the phones in between, so it can reach a teammate well beyond your own phone's range.

What Knit gives a team in the field

Every Knit phone relays for the others. A message hops from phone to phone until it reaches the person it's for, and if there's no path yet, it waits. Phones carry direct and group messages for up to a day and hand each one on as soon as a path opens.

Direct chats and group chats of up to eight people are end-to-end encrypted, so the phones that relay your team's messages can't read them. You can send photos, voice notes and files up to 8 MB. A location pin sends your position as coordinates with its accuracy, needs no map data to send or read, and opens in whatever maps app the other person has, offline maps included.

When typing is too slow, a mesh call works like a walkie-talkie between two people: hold to talk, release to listen, through up to three other Knit phones. It's one-to-one, so it's for a quick word with one teammate, not a channel for the whole team.

There's no account to make and no phone number to share, and the phone-to-phone mesh needs no server. Knit is open source and free.

Where it fits next to your radios

Keep your radios for the net and for anything everyone has to hear at once. Knit takes the traffic that's easier to read than to hear, and it tells you who has it: a group message shows "Delivered to 3 of 5", so you know who still needs a call on the radio.

It runs on the phones your volunteers already carry, and nobody needs a radio licence to use it. That matters most for the people who don't have a radio, such as a new member or the volunteer at the check-in table.

For search and rescue teams

A field team stays connected as it spreads out, because each phone in the line relays for the next. A phone-to-phone hop covers tens of metres in the open and less through trees or over a ridge, so walk the range in your own terrain at a training day before you count on it.

To reach a team beyond phone range, pair Meshtastic LoRa radios with Knit: one at base and one with each team. Short private messages, up to about 160 characters, go from one board to the other across kilometres, depending on terrain and antennas, and a mark shows when the other team's radio has received yours. A set of coordinates fits with room to spare. LoRa carries the short messages; group chats and photos follow over the phones once the team is back within range of base.

At staging, Direct file send hands a volunteer a large file, like an offline map of the search area, straight from one phone to another over Wi-Fi, up to 8 GB, with no internet needed.

Keep subject details in direct and group chats, where they stay encrypted. The Nearby room is an open channel that anyone in range can read.

For CERT teams and neighbourhood response

After an earthquake or a big storm, the cell network in your area may be down, or so busy that nothing sends. Knit doesn't use it. Phones talk directly, so the more neighbours and volunteers have it installed, the farther messages can travel across the area.

Give each squad a group chat of up to eight people for damage photos, the list of addresses checked and the location of the staging area. For an open call to everyone in range, like where water is being handed out, post to the Nearby room. It's public by design, so anyone nearby, residents included, can read it and answer.

Knit translates messages between English and Spanish, French, Ukrainian, German or Portuguese on the phone itself. Each language is a one-time download, and after that it works with no connection. A volunteer whose phone has a language can hand it to a teammate nearby with Direct file send, no internet needed.

For ARES and amateur radio operators

If you already run Meshtastic, Knit pairs with your board over Bluetooth. Its setup adds a Knit channel and leaves your primary channel alone, and the Meshtastic room shows that primary channel inside Knit, so you can read and post to it without switching apps. Knit keeps its own traffic to a tenth of the airtime on the shared frequency. In the US, Australia and New Zealand, a board can move to a frequency only Knit boards use instead, which gets the full airtime your region allows but gives up relaying by other Meshtastic radios.

Knit is built for a board on Meshtastic's standard, licence-free settings rather than its licensed mode. Whatever mode the board is in, Knit seals its own private messages over LoRa, and you can switch those off under Private messages over LoRa. Nearby posts aren't encrypted by Knit. Setup also renames the board to "Knit" plus four characters, so a callsign in its name won't survive.

Where it helps most is with the people around you who aren't licensed. Shelter staff, served-agency staff and other volunteers can message each other and the radio room from their own phones, while formal traffic stays on your voice nets and Winlink.

Get your team ready before the next callout

Install Knit at a team meeting, from Google Play, F-Droid or GitHub. On scene, the connection you'd need to download it is the one that's down.
Add each other in person by scanning QR codes. It works with no internet, and it marks each contact as verified.
For a big roster, a team member can run a private Internet relay and share one invite to a shared room. Everyone who joins becomes a contact in one step. Do this while you still have internet; after that, the team's direct and group chats work over the phones alone.
Make a group for each squad. A group's members are fixed when it's made, so make a new one when a squad changes.
Let Knit run in the background without battery restrictions, so each phone keeps relaying from a pocket.
Try it at a drill out where you'd deploy, not just in the car park.
Carry a power bank. A spare Android phone with no SIM can sit at a high spot as an extra relay.
If you'll use LoRa radios, pair and set them up in Knit beforehand.
Download translation languages while you're online.

Where Knit is the wrong tool

It isn't a way to call for help. Knit doesn't reach 911, dispatch or a rescue coordination centre. For help from beyond your team, use a phone call, a satellite messenger or a personal locator beacon.
It doesn't replace your radios or your comms plan, and no agency has approved or certified it.
Knit runs on Android 10 and newer. Knit for iPhone is in a closed alpha, so plan around Android phones for now. If volunteers with iPhones would like to test it, email hello@getknit.app.
Group chats hold up to eight people, and a group's members are set when it's made. There are no roles, admins or priority messages, and calls are between two people.
It doesn't track positions or show a map. A location pin is a one-off message.
Delivery is best effort. A phone hop is short, and terrain makes it shorter. The mesh holds direct and group messages for up to a day and Nearby posts for six hours.
The Nearby room and the Meshtastic room are open channels. Keep names and medical details out of them.
LoRa carries short private messages and Nearby posts, and a private message needs a board at each end. Content stays sealed, but which boards are talking, and when, can be heard by any radio in range.

Common questions

Is there an app our search and rescue team can use to text with no cell service?

Knit is one. It's a free Android app that sends messages, photos and locations between phones over Bluetooth and Wi-Fi, with no cell service or internet needed. Each phone relays for the others, so a message can reach a teammate beyond your own phone's range, and optional Meshtastic LoRa radios carry short private messages across kilometres. Teams run it next to their radios, for the traffic that's easier to read than to hear.

What can CERT volunteers use to stay in touch when the cell network is down?

Start with the radios in your comms plan. For text, photos and locations, Knit connects volunteers' Android phones directly over Bluetooth and Wi-Fi, with no network or radio licence needed. Squads can use group chats of up to eight people, and the public Nearby room reaches everyone in range. Install it and add each other before a disaster, not during one.

Can Knit replace our radios?

No, and it isn't meant to. Knit has no group voice channel, it reaches as far as the chain of Knit phones and radios between you, and delivery is best effort. Use it for what radios handle badly, like photos, exact coordinates and messages that wait for someone out of range, and keep your radios for the net.

Does Knit work with Meshtastic radios?

Yes. Knit works phone to phone on its own, and pairing a Meshtastic board over Bluetooth adds a radio hop measured in kilometres. Short private messages go from your board to your contact's, so they take a board at each end, and short Nearby posts cross too. What a board hears reaches the Knit phones around it. Group chats, photos and long messages stay on the phones or an optional Internet relay.

Can ARES operators use Knit with a board in licensed mode?

Knit is built for a board on Meshtastic's standard, licence-free settings rather than licensed mode. Whatever mode the board is in, Knit seals its own private messages over LoRa, and a switch in Knit's settings, Private messages over LoRa, turns them off. Nearby posts aren't encrypted by Knit. Knit's setup renames the board, so a callsign in its name won't survive.

Can we send exact coordinates with no map or data connection?

Yes. Knit's location pin sends your position as coordinates, with its accuracy, in any chat. It needs no map data to send or to read, and the person receiving it can copy the numbers or open them in any maps app, offline maps included. It sends one position when you tap it, never a live track.

Do volunteers need accounts, phone numbers or a server?

No. Knit has no accounts and doesn't use phone numbers, and the phone-to-phone mesh needs no server. A team can add an Internet relay to keep chats going when people are far apart, either Knit's public relay or one it runs itself, and that part is optional.

How many people fit in a Knit group chat?

Up to eight, including the person who makes it. Members are fixed when the group is made, so a team usually keeps one group per squad and makes a new one when a squad changes. The Nearby room has no limit, but it's open to anyone in range.