A decentralized peer-to-peer messaging application that operates over Bluetooth

3 hours ago (bitchat.free)

One missing feature: deferred message propagation. As far as I understand, while messages will be rebroadcast until a TTL is exhausted, there is no mechanism to retain in-transit messages and retransmit them to future peers. While this adds overheads, it's table stakes for real-life usage.

You should be able to write a message and not rely on the recipient being available when you press send. You should also be able to run nodes to cache messages for longer, and opt in to holding messages for a greater time period. This would among other things allow couriers between disjoint groups of users.

  • that is a super good callout.

    this is prob the 100th time ive read about bitchat here, and the comments are largely the same (use briarchat, none of these really work that well, i dont like jack dorsey, etc) every time.

    but this is interesting. and i agree strongly with this: "While this adds overheads, it's table stakes for real-life usage."

    i suppose events like iran are really making me wonder if this stuff is possible it feels like anyone who's under the chokehold of regimes has completely run out of options, but even in America I'm getting the sweats wondering if there's going to be a time where such techs are needed. from what i gather none of these decentralized p2p messengers work well at all, but I also haven't truly tried. I can think of some moments that would've been viable test grounds though. Was at Outsidelands festival in San Fran and cell service was pretty much DOA due to the volume of people trying to hit the same tower(s). Even airtags which everyone in the group had on their beltloop weren't working.

Could someone please explain in what situation do you use a BlueTooth messaging app? Like, even BT5 range won't exceed 400 meters. What good is this? You're not going to send images to journalists from protests with it (you'd do wisely to keep it in airplane mode until you get home and then you'd upload them to their securedrop or whatever), and you don't need off-band security to let the kids know it's dinner time.

  • One of these bluetooth messaging app was made by a developer who was on a cruise ship with family, and the Internet over satellite costs an arm and leg. So he wrote an app to communicate with his families over bluetooth.

    Also why would one want to have the data go over some servers thousands miles away when the device is right next to you? Seems like bluetooth is the perfect way to communicate for devices that are close to each other.

    • Yeah I can imagine a jam-packed cruise ship might be useful provided the signal propagates from deck to another (unlikely), but it's quite a niché use case.

      >Also why would one want to have the data go over some servers thousands miles away when the device is right next to you?

      Why would that matter? Use Signal to protect the content, or use Cwtch to protect content and metadata. If you need to exchange secret communications that mustn't go through some server, why not discuss f2f with no phones around? You'd also eliminate attack vectors where your (chances are, Chinese Android) device spies on you, as well as anyone who has compromised it to read messages from screen.

    • I remember a different app thats was used on e.g. festivals where the local broadcast cells where overwhelmed when a quite rural area suddenly had to server 50000 to 100000 additional people and 3g and 4G basically stopped working. I think it was called Firechat or something.

  • Back in the 2010s I used the 'Notes' applications to send messages via Bluetooth on my Sony Ericsson to chat with a girl in the next bunk.

    There was no signal in the remote Irish hostel so it was the perfect way to send messages covertly in the dormitory.

    Fun night!

  • Any situation when mobile internet cannot be used. That is not only protests, but also legal gatherings, i.e. street concerts, or places where mobile coverage is poor in general.

  • In Iran right now... Internet shut down while the regime keeps slaughtering people at the order of 4x9/11.

    • I think you need to try to get MUCH more video and photo footage out. I heard thousands have been killed.

  • In theory if as many people use bitchat as used whatsapp somewhere like central london, everyone actually could communicate in a fully decentralised manner - you're frequently in bluetooth range of other people's phones just walking around or even sat in your house.

    Would that actually happen? No, but it's an interesting thought experiment

    • So other users are broadcasting messages of third parties onwards? How many devices does it take to saturate the channel? What does this do for phone battery?

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  • I see two use cases: * Communication between protestors * Illegal activities, but here I can imagine that bluetooth range is too small

    • The use cases stem from groups needing coordination in roughly the same area, with no internet. Disaster recovery efforts fit this exactly:

      Doctors Without Borders feeding centers in a famine far from anywhere, searching for people in the rubble of a building following an earthquake, searching for people in a refugee camp, etc.

      Verizon went down in the US this past week - perfect use case for Bitchat (or Meshtastic with a repeater or some other LoRa BT network). Verizon goes down while you're at the mall or store or Disneyland or whatever and you can still text to find each other.

      300m max range with line of sight would cover something like when I go to visit my parents who live in a desert canyon with lousy mobile phone coverage, I can send a message that I'm at the gate and put the dogs in the garage.

      1 reply →

    • I remember reading that men and women in Saudi Arabia are forbidden from interacting directly in a bar setting. So instead they were using Bluetooth to covertly connect and communicate.

    • > Communication between protestors > Illegal activities

      Often one and the same since the first thing those in power try to do is make various activities by protestors illegal

    • This is simply an app that allows to communicate through bluetooth locally. Why are you saying its only two use cases are protesting and criminals?

      1 reply →

    • I remember when Telegram had a "Nearby" feature. I remember seeing many not-so-legal activities around me, even in the range of 1 km.

  • Consider if you live in Gaza. Israel has destroyed all the telecoms equipment across the Gaza strip (and everything else). You were ordered to leave your home by Israeli soldiers, but now the school you're sheltering in is being bombed. You may need to leave, but you believe there may be sniper drones outside.

    - You want to check in with people around you about what to do - You want to check on the health of your family, from whom you were separated

I'd consider this app a proof of concept, with limited practical applications. The story of using BT in a cruise ship to chat with family appears mythological. The reality is that most of our phones have onboard a class 2 device (that's the lower range, 10-20m), the real world has walls to reduce the range, and a cruise ship has metal walls, due an effect called Faraday's cage. In case of protests a jammer will silence all devices. Anyway I was thinking that in extreme cases we could modify our devices for communication methods at community level, for example creating a Wifi mesh network with routers, or some other longe range protocol (ex. LoRa).

I don't know. I do not like Jack Dorey's involvement. Not a big fan of his.

I'd rather use Briar (https://briarproject.org/)

What are good file transfer apps that can be used in similar scenarios? (to be clear about the usage model: communications on a plane)

* I see LocalSend and LANDrop frequently suggested on HN but in my experience they rely on having a central Wifi router. No good.

* Android's QuickShare comes included by default, but it's buggy. Just yesterday it failed on me (I'm on an uncommunicated boat): it was defaulting to Bluetooth, so I had to reboot both phones to finally make it work over Wifi Direct. Not to speak about the "oh damn, you have an iPhone" scenario. Not ideal.

Anything else? (to remark: for airplane-like situations so no access to Internet and no central router)

This has released tags since back to July 2025. Does anyone know if it's being actively used to exfiltrate news from Iran right now? (if someone's been living under a rock: [1][2])

[1]: https://news.ycombinator.com/item?id=46573384

This is an interesting enhancement using Meshtastic to expand the range of bitchat https://github.com/meshtastic/firmware/discussions/7542

  • My fantasy is a P2P network that people can use from their everyday devices. The internet is becoming far too controlled, we need an alternative that is harder to monitor and censor.

    • I don't think Meshtatic, or any Lora-based solutions operating in regulated spectrum, works in practice for chat while also abiding by the rules. In Europe (868MHz) and the US (915MHz) the transmissions allowed are so restricted that while you may send alerts you can't really "chat" and even less so in a group chat.

Jack Dorsey is definitely a smart guy, I believe there is a big reason behind it. I wish he will surprise us to make it capable global communication. But my question is how long it will take to work it for a long distance?

  • I think he’s just a guy who got a lot of money who can pay people to implement his sometimes weird, sometimes useful, often ill-conceived obsession with decentralization and a very lame version of “freedom”.

    Like, he quit BlueSky because he wanted it to be completely unmoderated which is, frankly, asinine. His view of what “censorship” means exists in a world along with spherical cows and no bad actors.

Thought this could have been used in Iran but I guess it was a bit immature still.

Seeing Jack committing to this repo is kinda wild to me. I also wish I had fuck-you money and could spend my day engrossed in whatever I find interesting

  • > wish I had fuck-you money and could spend my day engrossed in whatever I find interesting

    A good mental exercise is to calculate how much you'd need to survive indefinitely in a pocket of rural America or the third world. No international travel. No bells and whistles. Limited cuisine. But survival and leisure unlimited.

    When I've run the numbers for a comforable living, they've come to $300k (Vietnam, $12k/y) to $500k (West Virginia or Portugal $18k/y). But one could halve (or more) those figures by accepting standards of living our grandparents would have found adequate.

    Then you make a choice. That world. Or the one you have. (Or something in between.)

    Two-fifths of American households have a net worth over $300,000; more than half over $150,000 [1]. That means somewhere between a lot of and potentially most Americans have, on a global scale, fuck-you money. Just not fuck-you money to retain their status at the centre of the first world.

    [1] https://dqydj.com/net-worth-percentiles/

    • Coll idea. One thing: This numbers exclude healthcare costs as you get older this gets more expensive.

      For countries with free healthcare, it is usually limited to people working there or citizens and ( in the German case ) recognised refugees.

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    • American software engineers maybe. But I heard somewhere that most Americans live paycheck to paycheck or at most have a few thousand dollars in savings.

    • WV is probably heavily underrated. Such a beautiful part of the US.

My verdict is negative: BT has too limited a range. Can you communicate in a crowd? Yes, sure, the density of BT hosts can be very high, but can you imagine a crowd in the street communicating via messages instead of face-to-face? Can it handle communications for an entire city of a few million people with useful overhead? I strongly doubt it.

We've had interesting mesh network experiments in the past (maybe some here remember Fonera), and some are trying on various bands, e.g. World Mobile, but none of these can realistically work unless prepared and deployed in advance, which happens through public choices, meaning public networks built to be truly resilient, rather than centrally controlled.

So, while technically interesting, they are not realistically usable in civil war situations. Instead, it's interesting to think about how vulnerable surveillance devices are in these situations, like modern connected cars and smartphones, which can operate a mesh centrally, for example, to guide and block cars at strategic road junctions and centrally acquire location data from the "meat-bots" carrying smart devices with them.

If I were a citizen in a civil war, I'd be afraid of the connected car and would stay far away from my smartphone if I decided to take action. If I were the ruler of a country that can't make its own cars and smart devices, I'd block them by any means necessary due to the serious national security risk they pose.

We need open hardware and FLOSS imposed by law, making it ILLEGAL to sell black boxes and fund research for verifiable hardware. Not to believe that the latest mesh app is good for anything without giving a single thought to real-world use.

Every time I've logged into Bitchat, nobody appears to be online - across the entire United States.