This article originally appeared on ABACUS The Hong Kong protests have been as much about battles on the internet as on the streets. Telegram has proven the most popular communication app in the “ be like water ” toolkit of the leaderless protest movement, helping with spontaneous road blockades and adapting to quickly-changing conditions on the ground. But Hongkongers are also looking into other options, and one of them is messaging app Bridgefy. The app received a sudden surge of downloads over the past two months in Hong Kong, according to Apptopia. The most attractive feature of Bridgefy is that it works without the internet, instead relying on Bluetooth to create a mesh network. Bridgefy's co-founder and CEO, Jorge Rios, told Forbes last week that the app is usually downloaded for mass events when there's a chance that the internet will be spotty. This could mean a large sports game or a big concert… or a mass pro-democracy movement. We decided to test it on the streets of Hong Kong. On Sunday, thousands of protesters gathered in front of the US embassy in central Hong Kong to urge US officials and politicians to take diplomatic action against the city’s government. As expected, mobile internet speeds ground to a halt as the area filled up with people. That’s when I launched the Bridgefy app and turned on the Broadcast feature, which puts all the people within range of each other into one group. This could allow a group to spread out across a wide area while still being able to exchange messages. I sent the first message and waited. After 30 minutes, I received a reply: “Fight for freedom! Stand with Hong Kong!” The good news is it worked! I could now send and receive messages without having an internet connection. And then I discovered a completely different problem: A chat app isn’t much use if nobody’s actually chatting. I ended up only getting five replies to my queries. Meanwhile, Telegram groups were buzzing with activity, including updates on the vandalism committed by some protesters on the subway and their next moves. Even when I did get messages on Bridgefy, I encountered issues. The arrival times of messages would easily get mixed up, putting the conversation out of order (something I saw when I tested the app in the office, too). And the Broadcast function stops working as soon as you exit the app, so don’t expect background notifications with important updates. Bridgefy uses Bluetooth to communicate, creating a mesh network of devices to pass on messages. If that was a bit of meaningless word salad to you, think about it this way: Imagine that you’re at one end of a human chain that stretches over a mile long. You can’t shout loud enough to be heard by the person at the far end of the chain. But you can get your message to the person standing right next to you -- who can tell the person next to them, and so on, until it reaches the other end. That’s effectively how a mesh network works: Each device passes information on to the next device, and the next, and the next. In theory, as long as you have enough devices in range, you can bridge huge gaps with lots of tiny hops between phones… assuming those phones are using Bridgefy, of course. But that’s also the big disadvantage of a mesh network, which is that you’re reliant on an ad-hoc network where a gap in coverage can cause huge issues. To use the human chain analogy again: It doesn’t matter if people on your end are standing arm-in-arm if there’s a huge gap in the middle. If the message can’t bridge that gap -- or does so very slowly -- the system won’t work. We saw this in action when we conducted a quick test in the office among the Abacus team. I stood at one end, Xinmei stood at the other, and Thomas was in the middle -- bridging the gap between us. In theory, any message I send to Xinmei would be relayed by Thomas’s phone, as would any message from Xinmei to me. Perhaps the distances were too great, or there was too much interference from other devices. But in both direct messaging and Broadcast mode (with Airplane Mode switched on), the messages traveled slowly at best -- and at worst, sometimes out of order entirely, resulting in an utterly confusing conversation. Still, you can see why people started downloading the app. Bridgefy started gaining traction after two platforms that have been popular with protesters, messaging app Telegram and Reddit-like forum LIHKG , both faced large DDoS attacks in June and July respectively. Aside from that, during the massive and often violent protests over the last 3 months, mobile networks would frequently slow to a halt. It’s not the first time mesh networking apps have appeared during a protest in Hong Kong. During the anti-government Umbrella Movement in 2014, protesters turned to a similar app called FireChat when rumors circulated that the city’s government would shut down mobile networks. With this latest movement, protesters have been getting more creative. They’ve already turned to apps like Apple’s AirDrop, Pokémon Go and, believe it or not, Tinder to help spread their message. For more insights into China tech, join our Facebook group , subscribe to our Inside China Tech podcast , and download the comprehensive 2019 China Internet Report . Also roam China Tech City , an award-winning interactive digital map at our sister site Abacus .