What if everyone in Tiananmen Square had been carrying a smartphone? Among civil society groups, it's a common question, and one with far-reaching implications. Would technology make the people's movement stronger or easier to control? Does interconnection strengthen a crowd or distract it?

Protestors are showing the limits of Chinese web controls

This weekend in Hong Kong, we're finding out. Since Friday, the protests have pitted pro-democracy protestors against a central government that may be backing out of its promise for open elections. It's a test of how much power Hong Kong can have in the face of central China, with many in Hong Kong hoping to elect leaders with fewer ties to Beijing. But as the struggle has played out in the streets, it's also played out on the web as protestors begin to spread news through Twitter and organize online, showing the limits of China's heavy-handed web controls.

Like most modern movements, the Hong Kong protests have a strong presence online. Occupy Central, one of the biggest groups in the movement, has spread its message through a Wordpress blog where the group lists its manifesto, basic tenets and a manual for civil disobedience. Search for #occupycentral or "umbrella revolution" on Twitter and Instagram and you'll see a flood of photos from the protests, alongside Facebook-ready memes and plans for upcoming actions. It's easy to follow each event from your phone, amplifying the effect of each action and giving protestors a crucial voice as they press for concessions from the local government. When protestors organized to carry a black banner through the city streets, they could be sure it would attract attention internationally, whether local media covered the action or not.

The protest has gone far beyond what would be allowed on the web in mainland China, where the Great Firewall monitors and filters out any media deemed unacceptable by the government. One picture retweeted by the official Occupy Central account shows a man with an umbrella facing down a tank, a direct reference to the Tiananmen Square protests of 1989 and one of the biggest red flags for Chinese web censors. But since Hong Kong and Twitter sit outside the Great Firewall, the censors had no way to stop it.

Sina Weibo has seen a record number of posts deleted

Instead, mainland China has tightened the restrictions on the mainland web. On Sunday, the country blocked Instagram in an effort to slow the spread of protest photos, and Vine has seen intermittent problems as well. (The app appears to be back online, although its official status is still unclear.) Twitter has been blocked in mainland China since 2009, but the state-owned alternative, Sina Weibo, has seen a record number of posts deleted since the actions began, particularly any post using the phrase "umbrella revolution."

Protestors have already started bracing for similar restrictions in Hong Kong. The peer-to-peer texting app Firechat has an enormous spike in usage, with 100,000 new users since the protests began and as many as 33,000 simultaneous users in various chat rooms. Because Firechat can communicate from phone-to-phone rather than relying on a central data network, Firechat chat rooms could potentially survive even in a web blackout, like the ones that struck protests in Egypt, Turkey, and Ukraine. Tor metrics show an extra 500 people browsing the web anonymously as the protests began on Saturday, suggesting users in Hong Kong are also starting to think about evading web surveillance. At the same time, the new tools have come with new dangers. In one troubling report, the Code For Hong Kong group discovered a fake chat app designed to spread malware between protestors, using the same open network as a platform for attack.

Still, the rush of the last three days has shown how quickly a movement can grow when these tools are used effectively. In just 72 hours, the protestors have managed to define their goals and gain global prominence in the face of near-total opposition from established local media. The group has established symbols like the open umbrella that will have universal recognition for years to come. It's hard to imagine the message spreading so fast or so clearly without tools like Twitter, Instagram, and Wordpress. And while it's still too early to predict the ultimate effect of the protests, it's already one of the most substantial actions the region has seen in decades. As the last Chinese city outside the Great Firewall, Hong Kong is making the most of it.