By ByteBot
On January 8, 2026, Iran shut down the internet. 85 million people cut off, mid-protest. WhatsApp, Signal, Telegram—useless. But activists are still organizing. The tool keeping them connected is Briar, an open-source messenger that syncs via Bluetooth and Wi-Fi mesh networks, no internet required. It hit 252 points on Hacker News this week, and it’s easy to see why. When governments flip the kill switch, Briar is one of the few tools that actually works.
For developers, Briar offers something rarer than a working mesh network: a real-world example of delay-tolerant networking under fire. It’s open-source, Cure53-audited, and currently enabling coordination in a country where documenting protests can mean prison or worse. This isn’t academic. It’s infrastructure that matters when nothing else does.
How Bluetooth Mesh Actually Works in Practice
Briar doesn’t use servers. Messages sync peer-to-peer between devices using Bluetooth (around 10 meters), Wi-Fi Direct (up to 500 feet in clear conditions), Tor when the internet is up, or even USB drives when it’s not. The architecture is straightforward: each device acts as both client and relay. When two Briar users come within Bluetooth range, their devices sync messages. If you’re trying to reach someone across town, your message hops through intermediary users until it arrives.
This is delay-tolerant networking in action. It’s not real-time like Signal. Messages propagate through the network as devices move in and out of range. In a dense protest, that can mean seconds. In a sparse suburb, it might mean never. The protocol is called Bramble, and it handles handshakes, rendezvous, synchronization, and transport across all these different mediums. Contact verification happens via QR codes to prevent man-in-the-middle attacks.
What makes this work technically is the design assumption: connectivity is unreliable, potentially hostile, and worth trading convenience for resistance. When the internet is available, messages route through Tor to protect metadata. When it’s not, Bluetooth and Wi-Fi keep things moving. The system doesn’t try to be real-time because it can’t be. It accepts delay as a feature, not a bug.
The Hard Limits: Battery, Range, and Reality
Here’s what most mesh networking hype glosses over: Briar drains your battery about four times faster than a server-based messenger like Jabber. Constant Bluetooth scanning isn’t free. Running it all day isn’t practical for most devices. The 10-meter Bluetooth range means you need either tight clusters of users or a long chain of relays. And if that chain breaks—someone turns off Bluetooth, battery dies, leaves the area—your message stops moving.
This is why Briar isn’t replacing Signal for daily chat. However, it’s insurance for worst-case scenarios. When protests shut down cellular networks or governments cut internet access, that four-times battery drain and 10-meter range become acceptable costs. But for everything else? Signal is faster, lighter, and doesn’t require you to be within 30 feet of another user.
The use cases that work are the ones where density solves the range problem: protests, dense neighborhoods during outages, journalist coordination during shutdowns, or high-security communications where metadata protection matters more than convenience. What doesn’t work: rural areas, always-on messaging, or trying to replace your main messenger. Briar requires commitment, technical understanding, and a threat model that justifies the trade-offs.
Why This Matters Right Now
Iran’s blackout started January 8 at 8:30 PM local time. It’s been extended through at least January 23. During that time, the Committee to Protect Journalists reports journalists can’t verify safety or document abuses. The Human Rights Activists News Agency reports over 18,000 detained and more than 2,400 killed. Journalists can’t verify those numbers because they can’t communicate with sources. The blackout isn’t just about controlling information—it’s about hiding what happens when no one can see.
Tools like Briar stop being curiosities when governments weaponize connectivity. The activists using it aren’t installing it because they read a Hacker News thread. They’re using it because Signal doesn’t work anymore, and silence means invisibility. The technical limitations—battery drain, short range, delayed delivery—matter less than the ability to coordinate at all. This is the 1% scenario where mesh networking justifies its complexity.
It’s also a reminder that infrastructure decisions aren’t neutral. Centralized servers are convenient right up until someone blocks them. Decentralized protocols are clunky right up until they’re the only thing left. For developers, the question isn’t whether to build for the worst case. It’s whether you’re comfortable building systems that fail when someone powerful decides they should.
Security That Passed Review
Briar was audited by Cure53 in March 2017—the same firm that reviewed SecureDrop and Cryptocat. Six testers spent 13 days looking for holes in the cryptographic protocols and codebase. Their report called the crypto implementation “exceptionally clear and sound” with no vulnerabilities found. The source code quality was flagged as “rather exceptional,” and the developers demonstrated a “good understanding of vulnerability patterns and threats.” Several issues were identified and fixed before production release. A follow-up audit by Radically Open Security in February-March 2024 re-tested the Android and desktop clients and recommended the software for production use.
The project is funded by the Open Technology Fund ($361,100 as of 2018) and released under GNU GPL-3.0 for Android and GNU AGPL for the desktop version. The code is public. The audit reports are public. For developers, this is what production-grade decentralized communication looks like when it’s done seriously.
What Briar Is and Isn’t
Briar is not a Signal replacement. Moreover, it’s not trying to be. Signal is faster, more convenient, and works anywhere you have data. Briar is what you install before the blackout, not after. It’s the tool that sits dormant until traditional messengers stop working. In most scenarios, that never happens. In Iran right now, it’s happening to 85 million people.
The competitive landscape includes Bridgefy, optimized for large temporary gatherings like concerts and protests, and Bitchat, launched in 2025 with a consumer-friendly approach to Bluetooth mesh. Each has trade-offs. Briar prioritizes security and metadata protection over ease of use. Bridgefy prioritizes event coordination. Bitchat prioritizes simplicity. Your threat model dictates which one matters.
Mesh networking has real limits. Bluetooth range is physics, not software. Battery drain is thermodynamics, not bad code. User density requirements mean sparse networks fail. Nevertheless, those limits don’t make Briar irrelevant. They make it specialized. When activists in Tehran need to organize despite government surveillance and internet blackouts, specialized is exactly what works.
The Developer Takeaway
Briar demonstrates what’s possible with delay-tolerant networking and what still isn’t. You can build mesh networks that work in practice, but they require users to accept trade-offs most people won’t. Battery life, range, speed—pick two. The Bramble protocol suite is worth studying if you’re building anything that needs to work when infrastructure fails. The audit reports show what serious security review looks like. The deployment in Iran shows what happens when theory meets necessity.
This is infrastructure that matters in the margins: high-risk scenarios, authoritarian crackdowns, natural disasters. It’s not going mainstream because it sacrifices too much convenience. But convenience isn’t the only axis that matters. Furthermore, when governments shut down the internet to hide what they’re doing, tools like Briar stop being academic projects and start being survival infrastructure.
If you’re building communication tools, the question isn’t whether your users will ever need this. It’s whether you’re comfortable knowing they won’t have it if they do.
