As the spirit of rebellion was rekindled on the streets of Hong Kong during last year’s Occupy Central pro-democracy protests, it was an app called, fittingly, FireChat that helped the demonstrators stay in contact when their phone or internet signals went down. When users are connected to the internet, FireChat works like any other messaging app. But when the signal is weak or absent, it comes into its own, using Bluetooth or Wi-fi to bounce messages between phones until it can find an internet connection and be whisked off to its intended recipient. The app saw a record number of sign-ups in Hong Kong after rumours abounded that police would shut off phone networks during the early days of the Occupy Central protests. "What happened in Hong Kong last year was really unexpected for us," said Micha Benoliel, co-founder and chief executive of FireChat parent Open Garden. Benoliel said that the app now has more than 500,000 users in Hong Kong, or around 7 per cent of the population. This more than satisfies the 5 per cent density that FireChat estimates is needed for its offline messaging feature to work effectively. FireChat was originally intended for use at concerts or in rural areas where internet access may be spotty. Its adoption as something of a political news sharing tool created some unexpected problems for Open Garden. It was also used by protesters in Iraq and Ecuador last year. "We had to adapt very quickly," said Benoliel. "At that time, we only had public messages with big chatrooms." One of the first features introduced was verified profiles, similar to Twitter and Facebook, so users could know that accounts sharing news or other key information were trustworthy. On Thursday of this week, FireChat rolled out private messaging, a feature that raised a host of new problems in itself. Previously, messages were transmitted to public chatrooms and not encrypted, which led to criticism from security experts. With private messaging, encryption and security had to be front-and-centre, as messages may be stored and transferred between multiple phones before they reach their intended recipient. "All FireChat private messages are encrypted from end-to-end," the company said in a statement. "Only the sender and the recipient can read a private message." The private messaging system means FireChat can compete with established messaging apps like WhatsApp or Facebook Messenger. "You can use FireChat as any other messaging app, but where other apps fail, FireChat will work," said Benoliel. As the company's second-largest market after the US, Hong Kong is of key importance to FireChat as the app struggles to overcome the catch 22 of all new social or messaging apps: attracting enough users to generate momentum. One way of overcoming this hurdle would be to preinstall it on smartphones. Benoliel said FireChat is in talks with phone manufacturers and telecoms companies to do just that, particularly in emerging markets. "Even the big carriers [in emerging markets], they can see this technology as a way to onboard more people at a very low cost," he said. "Instead of installing a very large infrastructure" in places where coverage may be limited or unreliable, telcos can encourage customers to use FireChat, allowing them to "increase their reach with a minimal investment", he added.