How it works

How can it work without internet?

Phones talk to each other directly over Bluetooth. There is no server in the middle. If a Yonder phone is in range, you can chat with it.

How does a message reach someone further away?

Phones carry messages for each other. Your message hops through other Yonder phones until it reaches the recipient. Carriers hold it encrypted for up to a day and cannot read it.

What if the phone carrying my message walks away, or I am gone before it arrives?

When two roads to someone are known, your message takes both, so one phone walking away does not matter; one clear road alone gets one copy. With no road, it goes only to phones likelier to meet them (from the last 48 hours of meetings); when nobody has heard of them, to up to four, chosen by signal, stability and movement. A phone that keeps taking messages and never delivers any is passed over. Each carrier hands it to new phones that lack it, for up to a day; your own phone keeps trying for 7 days, and if no proof comes back in the time the road should take it adds one more path. Under your bubble you see 'Handed to 2 phones to carry' while it is out there, then the tick. Nothing is promised that the radios have not confirmed.

How far does it reach?

Bluetooth: roughly 30 to 60 metres between two phones at hand height in the open, and about 100 to 250 metres with long range (on by default on phones with Bluetooth 5), less through walls, trees and crops. Height helps more than any setting: a phone on a dashboard, a window sill or a post above the crop line sees much further. Every Yonder phone in between extends the reach.

What is long range?

Bluetooth 5 phones have a slower, farther-reaching radio mode (Coded, about 2 to 4 times the distance). Yonder keeps quiet links on it and switches to the fast mode only while a file moves over a strong link, then back. A weak link never leaves long range, and a link is never closed just for a weak signal. Settings → Network → Bluetooth → Long range turns the default off (links then start fast and slow down only when weak). Phones without it are reached at normal range.

What is Wi-Fi Direct for in Yonder?

Speed, and reach without Bluetooth. Bluetooth stays the mesh: it finds everyone and carries every message; when a phone nearby has Bluetooth off, Wi-Fi Direct carries the mesh to it by itself (see My Bluetooth is off). Wi-Fi Direct adds a fast link, many times faster than Bluetooth, used by itself whenever it is up, and it reaches further than Bluetooth. To link with a contact within Bluetooth reach, tap the Wi-Fi icon at the top of their chat (no prompt on either phone); while linked, the same icon asks before it disconnects you. Without Bluetooth (out of its range, or switched off): Connect on their device in Settings → Network → Wi-Fi → Devices in reach, as in Android's own Wi-Fi Direct settings; Android asks its owner to accept on their phone, and once they do the two Yonders link and chat, send files and carry the mesh as over Bluetooth. Someone who is not your contact is linked like a Bluetooth neighbour: you can add each other, and big files and full-quality photos stay between contacts. Disconnect ends it on both phones; nothing links it again by itself (except, from 0.0.84, to deliver what you send while no other radio links you), and either of you can tap the Wi-Fi icon to connect again. Outside mesh groups (see My Bluetooth is off), the first link with someone is always a person's doing, and a link a mesh group made does not count; after that, Connect automatically (on by default) links by itself when a photo, video or file of 256 KB or more goes between you, or when your messages wait for them and their phone is in Wi-Fi Direct reach but out of Bluetooth's, and Keep Wi-Fi Direct warm (off) links you by itself while you are near each other. Every Wi-Fi Direct link, made by Connect or by itself, lets go once nothing has gone between you for 7 minutes (messages, typing, a file moving; an open chat or being near does not count), on both phones together and never while a file moves; it comes back when something new goes between you or either of you taps the Wi-Fi icon, and messages go over Bluetooth meanwhile. Links that exist only through a mesh group (a phone nearby with Bluetooth off) follow the mesh group's own rules instead. A link that breaks by accident (not by Disconnect, the 7 minutes or Wi-Fi switched off) reconnects at once while something wants it; one that keeps breaking waits 15 s, 30 s, then a minute between tries, less as soon as their phone shows up again. While you are linked it carries everything between the two of you: messages, typing, receipts and files, and Bluetooth carries nothing twice. A file of 101 MB or more to a contact waits for the link and sets it up itself. Within Bluetooth reach there is no pairing and no Android dialog: the phones agree over Bluetooth which one makes a private Wi-Fi Direct network, and its name and password (fresh each time on Android 10 and later) go encrypted to the other phone, which joins with them. Files go at the link's own speed. Settings → Network → Wi-Fi has its switches and, folded under one row, the devices in reach now. It needs Wi-Fi switched on (not connected to anything), and on Android 12 and older Location on too; Yonder never switches Wi-Fi on. Phones on Android 9 and older can make a network but not join one by its password, so two of them link only with Connect on the device (Android's own invitation). A phone already connected to a Wi-Fi network may use a slower channel, or refuse, depending on the phone. It costs some battery while linked. With several contacts nearby, the phone with more of them around hosts, so others can join it (up to four at once). Linked with one contact, tap the Wi-Fi icon in another's chat: if they can join the group you are in, they join and nobody is dropped. If they can't (your phone is someone's guest, or they lack the 5 GHz your group uses), the chat says Switching Wi-Fi Direct here in 5 s, with Cancel; tapping again does not make it longer, tapping a third contact switches to them instead on the same 5 s, and Connect for the contact you are linked with cancels it. Then that link ends (their phone is told), Android closes the group (the chat says so while it does), 5 s to settle, and the new link. A file going to a third phone in the group holds the switch until it is done (the chat says so); a file with the contact you leave pauses, kept, and goes on later. Opening a chat never does any of this.

Can anyone else read my messages?

No. Each message is encrypted for exactly one phone (AES-256-GCM, with a key from both phones' encryption keys and, a fresh one-time key for every message) and signed by your identity key. Phones that carry it see only whom it is for, when it was written and its size. The radio link itself is also encrypted, so someone listening to Bluetooth gets nothing readable, not even names.

Can other apps or devices talk to Yonder?

No. Yonder looks only for Yonder's own Bluetooth signal, and a link counts only once the other phone has introduced itself. Between two Yonder phones, each one proves on every link that it holds its own identity key (a recorded or copied greeting does not pass), and everything on the link is then encrypted with keys made for that link alone. A device that greets wrongly or talks before introducing itself is cut off at once and ignored for half a minute, then longer each time it does it again (up to 10 minutes), and only a few unintroduced links may wait at a time, so a stranger cannot spend your battery or radio. A phone that proved itself before is never accepted again on an unverified link. Honest limit: anyone can write software that speaks Yonder's protocol with its own keys; it then counts as one more Yonder phone, held to the same limits.

Does it need an account or a phone number?

No. Your identity is a pair of keys created on your phone. Nobody registers anything anywhere.

Does Yonder collect anything?

Nothing reaches the developer: no account, no analytics, no crash reports sent, no identifiers. The only internet use is downloading map pictures and place search while you are online. A diagnostic log stays on your phone and leaves it only if you share it. Read the privacy policy under Settings.

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