Two phones cross paths. Nothing else travels.
Here, without the marketing, is what the app really does: what your phone broadcasts, what it listens for, what the server does with it, and what the other person can see of you at each stage.
1. Your phone broadcasts an anonymous token
In the background, ProxiBlu broadcasts a sixteen-byte beacon over Bluetooth. It is not your name, not your account number, not a location: it is an encrypted block, unreadable to anyone without the server's key.
That beacon changes every fifteen minutes. A hostile device parked on a street could not follow you: from one window to the next, nothing shows that it is the same phone twice. The app downloads a week of beacons in advance, which is what lets it keep working with no network at all.
Bluetooth carries nothing else. No photo, no profile field, no GPS coordinate goes over the radio. It exists only to establish that two phones were physically close.
2. It listens, and notes what it hears
At the same time, the app listens for other people's beacons. For an encounter to count, the signal has to be strong enough: we average several readings over a few seconds, which works out to roughly a few metres — the same room, or the same sidewalk. Not through a wall, not from one floor to another.
These observations pile up in a local queue on your phone and are sent to the server in batches every few minutes, over HTTPS. If you're on the subway with no signal, they wait their turn.
Only one of the two phones needs to have seen the other for the encounter to exist. That avoids missed connections when one device was in a pocket or in deep sleep.
3. The server works out who crossed whom
Only the server can decrypt a beacon and find the account behind it. Along the way it checks that the beacon is genuine, that it belongs to the right time window, and that neither account has blocked the other. Then it creates the encounter on both sides and notifies you both.
A cooldown stops you from endlessly re-encountering the same person: if you see each other every morning on the same bus, the app spaces those encounters out, and the person's card simply shows how many times you have crossed paths.
The raw observations are destroyed as soon as they're processed. Only the encounter itself remains.
4. Your filters apply before you see anything at all
Gender preference and age range are applied on the server, at the moment the encounter is created. Someone outside your criteria isn't “hidden” — they don't enter your list in the first place. Gender preference is never overridden, by any plan; a paid plan can only widen, by a few years, the age range in which you appear.
This visibility is fixed on each side and can therefore be asymmetric: you may see someone who cannot see you, because their own criteria don't include you.
An encounter that filters set aside stays known to the server for a few days, with no location. It is only shown to you when you ask for it yourself: in “Find a gang you crossed via Bluetooth”, which suggests the people you spent an evening with, whatever your dating criteria, and in “Live”, which shows the people around you, without your filters, for 10 minutes to 1 hour.
5. The thumb, the match, then the contact details
Your list shows only the day of an encounter — “today”, “yesterday”, “3 days ago” — never the time, nor the place. Each card carries three gestures:
- The thumb — you'd like to match with this person. You can take it back as long as they haven't answered.
- The star — keep them in your favourites. It's a private gesture, and a favourite never expires.
- The trash can — remove the encounter from your list. You have 24 hours to put it back, from “Deleted encounters”.
A legend recalls these three gestures: at the top of the list for your first two days, then at the bottom. The heart, for its part, stands for matches.
Screens shown in French. The app is available in English and 29 other languages.
Recent or Live. At the top of the Encounters tab, “Recent” shows your usual list, according to your search filters. “Live” shows only the people around you right now, detected over Bluetooth in the last few minutes, and without your search filters: for 10, 20 or 30 minutes or 1 hour, as you choose. At the end, the screen goes back to Recent on its own. It's made for a bar, a night out or a festival: the list updates by itself, and someone who has left stays listed for up to 5 minutes after they were last detected. The thumb, the star and the trash can work as usual. The third tab, “My places”, is explained below, and each tab opens with a short explanation, “What is this tab for?”, that you can fold away.
During Live, settings of its own narrow the list if you want, without touching your search filters:
- three chips, “Man”, “Woman” and “Other” — none selected means everyone;
- an age slider, separate from the one in Recent;
- “Up to N people”, from 10 up to your plan's limit, marked with a padlock: 50 with the free account, 100 with a paid plan. The server keeps the closest ones, without ever saying who is closest.
Your friends aren't encounters. As long as you're friends, a friend doesn't appear in your Recent list, and crossing paths with them sends you no notification. In Live, a friend who is around still shows up, marked “Friend”, with no thumb: you don't like a friend.
You can also switch everything off. The “Turn on encounters” switch, behind the gear icon in the Encounters tab and in Settings, stops encounters: when it's off, you don't cross paths with anyone and no one crosses paths with you, even with Bluetooth on. A red “Encounters turned off” banner reminds you, and the encounters you already have stay. The setting applies to this phone.
Without a mutual like, the encounter leaves your list by itself — after about 36 hours on a free account, 4 to 10 days on a paid plan. The app never tells anyone who liked them until it's mutual. One deliberate exception: the Super Like on paid plans moves your like back up the person's list, and they may then guess it came from you.
Two thumbs make a match. It opens the full description and the conversation. But not the contact details.
The two-step match. Your number, your Instagram, your Facebook or your Telegram only become visible once both of you have tapped “Share my contact details”. It is a separate consent, deliberately irreversible, and it is never behind a payment.
6. Around my places: people who frequent your areas
An encounter means you were in the same place at the same time. “Around my places” also shows you people who frequent the same areas as you, with no encounter needed. You'll find it in the Encounters tab, under “My places”, the third tab at the top, next to “Recent” and “Live”; the gear icon in that tab and Settings lead there too.
It isn't GPS tracking: you set by hand up to three places you frequent, such as work, the gym or a café, each with a radius you choose — between 1 and 5 km by default, limits the team sets. The Free plan allows two places, paid plans three.
You tap the map to place the centre, or search for an address, then choose the radius. Every place comes with three safeguards:
- a rounded centre: the server rounds it to a grid — 500 m by default — before storing it, so the exact address is never kept;
- a minimum radius, 1 km by default, which stops anyone from targeting a single block;
- a private name, “just for you”, encrypted on the server.
Today's list. The tab shows you people with a place that matches one of yours. Each card shows the public profile — age, gender, height, hair… — and “Frequents your areas”: never their places, nor the distance. The magnifier filters the list by attributes, a word of the tagline, or which of your places the person joins — on your phone: nothing is sent to the server, and your daily profile limit stays whole. You like with a thumb or skip with a cross. Two likes make a match, with no encounter, and its profile says “You both frequent the same areas.” A like given to someone you crossed paths with and a like given here answer each other too. The list refreshes every day, and how many new profiles you get per day depends on your plan: 15 on Free, 40 on Premium, 100 on Premium+, no limit on VIP.
When do two places match? When the distance between their centres is less than the smaller of the two radii. A 1 km place and a 5 km place therefore match only if their centres are less than 1 km apart. Everyone keeps control of the distance: small circles only show you people who are truly close, and large circles impose no one on someone who chose small ones.
Filters (the age and gender you're looking for), blocks, and people skipped or already matched apply on both sides, and your friends don't appear there. From a profile on the list, you can report or block, as anywhere else.
Circles you can't move around at will. So that no one can shift their circles to locate someone:
- a place moves — centre or radius — only once every 7 days, a delay set by the team. The first placement has no waiting period, a correction stays possible for 15 minutes after placing it, and renaming a place is always allowed;
- removing a place does not reset the delay. Until the delay ends (7 days at most), the removed place is kept, hidden, matching no one, and “Put this place back” restores it as it was. After that, it is erased, and another place can take its spot;
- a place not confirmed for 90 days is paused: it no longer brings up anyone, and you no longer see anyone through it. A reminder appears in the tab, and “Confirm my places” reactivates them.
The dynamic place, for a festival. At a festival or a big event, places with a radius of at least 1 km, which move only once a week, are no use. On top of them, you therefore have one dynamic place, which doesn't count among your plan's places:
- “Update my dynamic place” sets it where you are, from your phone's GPS, accurate to 20 m or better — otherwise nothing is sent; “Choose on the map or by address” sets it on the point you pick;
- its radius is 50 m, it lasts 24 hours, and it can be updated once a day;
- it only matches other people's dynamic places: in the same daily list, you see the people whose dynamic place is within 50 m of yours, and they see you.
You'll find it in “Edit my places”, below your places, and through its icon — a target — in the row of tools in Recent and to the right of “Places set”, at the top of the “My places” tab. Its centre is rounded to the nearest 10 m; no one sees it, and its coordinates are erased from the server within the hour after it ends — right away if you remove it.
Where your places stand. At the top of the tab, “Places set: 1 of 2” tells you how many places are set out of those your plan allows, then, line by line, each one — “Set”, “Not set” or “Paused” — and your dynamic place. Tap “Not set”: the app opens that very place, ready to set. An empty list often comes from there: for two people to see each other, both must have set their places.
The feature is optional: nothing is set in advance. Turning off “Around my places”, at the bottom of the “My places” screen, erases all your places from the server; deleting your account erases them too.
No one sees your places or how far away they are; each person only knows which of their own places matches. A usual place never pinpoints an address, and it isn't an encounter. On the server, the rounded centre is stored in the clear, since that is where places are compared — to the nearest 500 m for your usual places, to the nearest 10 m for your dynamic place, for as long as it lasts; their names, on the other hand, are encrypted. On your account's record, the team sees only how many places you have, their dates and until when your dynamic place is active — never where.
7. Messages we cannot read
The conversation is end-to-end encrypted. A message is encrypted on your phone with the other person's public key and can only be decrypted by their device. Your private key stays in your phone, and your app warns you if the other person's key changes.
In practice: our servers store an opaque encrypted block and pass it along. Faced with a lawful demand from authorities, we can provide metadata — who wrote to whom, and when — never the text, because we don't have it. There is no quota: once you match, you write to each other without counting.
Photos are an exception on one point. An image attached to a message is analyzed automatically once, before it is encrypted, to screen out nudity and violence. That check does not keep the image; it then travels encrypted, like everything else.
The server is a queue, not an archive: a delivered message is purged within 30 days. The real archive of your conversations is your phone.
Only one phone at a time reads your messages. If a message reaches you encrypted for another key of your account — open on another device, or reinstalled —, the app recognizes it and asks the person who wrote it to send it again, on its own: their phone encrypts it again for yours — after they confirm, if your key has changed — and it becomes readable. This works for messages less than 7 days old, a delay the team sets. We can't do it in their place: we have no key that opens your messages.
A typo? For 15 minutes after sending — a delay the team sets — a long press on one of your messages offers “Edit” and “Delete for everyone”, with a match, a friend or in a group. The correction travels end-to-end encrypted, like a message: the other person sees the new text, marked “edited”, or “This message was deleted.” in its place. An image can't be edited: it is deleted for everyone, then sent again. And the other person may have read the message before.
So you don't lose everything when you change devices, you can turn on account backup: conversations, images and your encryption key are encrypted on your phone with a password only you know, then stored on our servers. Neither we nor anyone else can open it — and if you forget that password, it is lost for good.
8. Before you meet in person
An online connection eventually becomes a real one. The app is built for that moment:
- Going to meet — from a match's profile, you fill in the place, the date and time, and a comment if you like. If you accepted geolocation, your phone sends your precise location to the server right away, then 1 h, 30 min, 10 min and 5 min before, at the time of the meetup, and every 15 minutes for 6 hours; “Stop sharing” ends it at any time. You can let one or more friends from the app know: they get a message with the place and time, then see the meetup and your location, at the same times, on your profile, until 24 hours after the sharing ends. The person you're meeting knows nothing about it. Without your geolocation consent (“Later”), the meetup is declared with no location.
- Safety location sharing — separately from “Going to meet”, you send someone you trust a link, valid for 1 to 12 hours, that follows your live location. The link shows a position and timestamps, never your identity or the other person's, and switches itself off at the deadline.
- Blocking — immediate, silent, effective both ways, and it expires both accounts' beacons so you can never cross paths again.
- Reporting — from a match or from a plain encounter. Every report is read by a member of the team, and an account that accumulates them is automatically pulled from other people's encounters pending review.
What “Going to meet” changes for your privacy. Unlike your messages, these locations are not end-to-end encrypted: they are in the clear on the server, and the team can look at them on your account's record, as a safety trace. They are kept six months, then erased, and could be shared with authorities on a valid legal request in the event of an incident. Removing the meetup erases it; it is included in the copy of your data (“Download my data”).
9. And as a group
Encounters aren't only for dating. The Social tab uses them to get the group from a night out back together, to plan events and to run groups, and the Connections tab brings together your matches and your friends. The privacy rules there aren't quite the same as in a private conversation: the Social page explains who can read what.
Introducing someone you crossed paths with to your friends. From an encounter's profile, “Introduce to my friends” suggests that person to the friends you choose — if they allowed it: the “Let people introduce me to their friends” setting, behind the gear icon in the Encounters tab, is off by default. They get a request for each friend and decide; accepting counts as a like toward that friend, who then sees them under “Encounters shared with you”, in the Connections tab, and can like them in turn: two likes make a match “introduced by a friend”. As for you, you only see “Request sent”: you never learn their answer. It works like showing a match to your friends.
Introducing a friend to your other friends. From a friend's profile, “Introduce to my friends” works the same way, with no setting to turn on: your friend accepts or declines each introduction — and this time, you know what they answered. The friend you introduce them to sees them under “Friends shared with you”, in the Connections tab; two likes, and it's a match “introduced by a friend”.
10. What about the battery?
Bluetooth listening is designed to be frugal: by default, the radio listens only about a quarter of the time. Four settings let you strike your own balance between responsiveness and battery life — from the low-power mode, which wakes up as soon as another ProxiBlu phone is spotted, to continuous listening.
During “Live”, it's the opposite: on Android, the radio goes to its maximum, for listening as well as broadcasting, so that people who arrive show up quickly. The battery drains faster for the length of Live, then everything goes back on its own.
A persistent notification tells you detection is running — Android requires it, and it is also honest: you always know when the app is working. If detection stops, a banner warns you and explains what to do, with steps tailored to your phone's brand.
11. What the app does not do
- It tells no one where you are, unless you choose to. If you accepted geolocation, the approximate area of an encounter — about a hundred metres — is recorded for your safety. It is shown to no one, any more than the time is. Your location is only shown when you decide: when you share it with someone you trust or a friend, or when you declare a meetup with “Going to meet”. In that last case, your precise locations are kept in the clear on the server, open to the team, and visible to the friends you let know (see above).
- It sets no place for you. “Around my places” is optional and isn't GPS tracking: you set your places yourself, by hand, and your dynamic place with one tap, when you decide to. The server rounds their centre, and no one sees them, nor how far away: each person only knows which of their own places matches.
- It does not tell you whether the other person saw you. Whether an encounter was detected by one side or both stays internal: showing it would amount to telling you “this person never noticed you”.
- It does not verify anyone's identity or background. An encounter proves physical proximity, not good intentions. Stay careful.
- It does not sell anything. No data is handed to brokers or ad networks for targeting.
All that's left is to try it.
The hard part is already done: you cross paths with dozens of people every day.