Media Releases

Researchers Expose Censorship on Popular Chat App, WeChat

December 1, 2016

Toron­to, ON – Researchers at the Uni­ver­si­ty of Toronto’s Cit­i­zen Lab are pub­lish­ing a report today that reveals how WeChat (the most pop­u­lar chat app in Chi­na) cen­sors con­tent. The results show WeChat has sep­a­rate cen­sor­ship poli­cies for users in Chi­na and inter­na­tion­al­ly, with the major­i­ty of cen­sor­ship tar­get­ed for Chi­na accounts, and has removed noti­fi­ca­tions to users about the block­ing of chat mes­sages on the plat­form.

The researchers also found that there is more cen­sor­ship in “group chat” mes­sages com­pared to one-to-one user chats, pos­si­bly due to con­cerns about posts being spread to larg­er audi­ences and lead­ing to mobi­liza­tion, and that WeChat’s built-in brows­er also blocks cer­tain web­sites for both Chi­na and Inter­na­tion­al accounts.

WeChat is the dom­i­nant chat appli­ca­tion in Chi­na and fourth largest in the world, with 806 mil­lion month­ly active users. The appli­ca­tion thrives on its huge user base in Chi­na, but like any oth­er appli­ca­tion in the coun­try it must fol­low strict con­tent reg­u­la­tions.

“Atten­tion usu­al­ly focus­es on for­eign com­pa­nies attempt­ing to reach into Chi­na and fac­ing hard deci­sions over how to approach its strict con­tent reg­u­la­tions. WeChat has

the oppo­site dilem­ma. To gain wider suc­cess the app must main­tain its base in Chi­na, all while stay­ing with­in the Chi­nese government’s bound­aries, and present a com­pelling expe­ri­ence to attract inter­na­tion­al users,” says Masashi Crete-Nishi­ha­ta, Research Man­ag­er, Cit­i­zen Lab, Munk School of Glob­al Affairs, Uni­ver­si­ty of Toron­to

The report finds that WeChat enables key­word fil­ter­ing for users with accounts reg­is­tered to main­land Chi­na phone num­bers. Remark­ably, the researchers found that cen­sor­ship stays on even if users switch to a non-main­land phone num­ber or trav­el to a dif­fer­ent coun­try — “lock­ing in” users with main­land Chi­na accounts to its sys­tem of cen­sor­ship no mat­ter where they go.

“It’s unclear if the per­sis­tent con­tent restric­tions we’ve detect­ed for Chi­na accounts is inten­tion­al, but the out­come is con­cern­ing. If you reg­is­ter a WeChat account to a Chi­nese phone num­ber you will always be under addi­tion­al cen­sor­ship, even if you trav­el or lat­er link your account to an inter­na­tion­al num­ber. The idea that you can’t escape a cen­sor­ship sys­tem imposed on you at the time of reg­is­tra­tion is a trou­bling one indeed,” explains Jason Q. Ng, Research Fel­low, Cit­i­zen Lab, Munk School of Glob­al Affairs, Uni­ver­si­ty of Toron­to.

The researchers sys­tem­at­i­cal­ly test­ed a sam­ple of key­words in two WeChat modes: one-to-one

chat and group chat. They found a greater num­ber of key­words blocked on group chat, which sug­gests that group chat is specif­i­cal­ly tar­get­ed, poten­tial­ly because of its abil­i­ty to reach a larg­er num­bers of users. Cen­sored key­words spanned a range of con­tent, includ­ing cur­rent events, pol­i­tics, and social issues. The report also found that cen­sor­ship on WeChat is dynam­ic. Some key­words that trig­gered cen­sor­ship in our orig­i­nal tests were lat­er found to be per­mis­si­ble in lat­er tests. New­found cen­sored key­words also appear to have been added in response to cur­rent news events.

“When you send a mes­sage on WeChat it pass­es through a remote serv­er that con­tains rules for imple­ment­ing cen­sor­ship. If the mes­sage con­tains a key­word or set of key­words that have been tar­get­ed for block­ing, the mes­sage will not be sent,” explains Jef­frey Knock­el, Senior Researcher, Cit­i­zen Lab, Munk School of Glob­al Affairs, Uni­ver­si­ty of Toron­to

The report goes on to detail how, in both one-on-one and group chat, cen­sor­ship now hap­pens with­out user noti­fi­ca­tion. Pre­vi­ous­ly, if a user sent a mes­sage with a black­list­ed key­word a warn­ing would pop up explain­ing the mes­sage could not be sent. Now mes­sages are cen­sored with­out giv­ing any indi­ca­tion that it has been blocked.

“The removal of the cen­sor­ship notices means WeChat has become even less trans­par­ent and also less depend­able for its users in how it han­dles their com­mu­ni­ca­tions,” says Lotus Ruan, Research Fel­low, Cit­i­zen Lab, Munk School of Glob­al Affairs, Uni­ver­si­ty of Toron­to

In addi­tion to key­word cen­sor­ship, WeChat imple­ments a URL fil­ter­ing sys­tem in its built-in brows­er. The researchers found 41 web­sites blocked exclu­sive­ly for Chi­nese WeChat accounts, includ­ing online gam­bling, news and media web­sites that crit­i­cal­ly report on Chi­na, and the web­site of the Inter­na­tion­al Con­sor­tium of Inves­tiga­tive Jour­nal­ists (, which report­ed on the Pana­ma Papers. All of the sites that were exclu­sive­ly blocked on Chi­na accounts were ful­ly acces­si­ble on Inter­na­tion­al accounts with­out any warn­ing page, but the researchers also found inter­mit­tent block­ing of gam­bling and pornog­ra­phy web­sites on Inter­na­tion­al accounts.

Unlike chat cen­sor­ship, when a web­site is blocked on WeChat a vari­ety of explana­to­ry mes­sages are pro­vid­ed for why the cen­sor­ship has occurred. How­ev­er, it is unclear how accu­rate­ly the pur­port­ed expla­na­tions match up with the actu­al rea­sons for why web­sites are blocked. This ambi­gu­i­ty in tru­ly attribut­ing the source for the fil­ter­ing again reflects the lack of trans­paren­cy in how WeChat deter­mines what “sen­si­tive con­tent” to block.

Over­all, this report shows the impor­tance of under­stand­ing how the apps we use every­day actu­al­ly work.

“Days are long gone when we used to inter­act with the Inter­net as an undif­fer­en­ti­at­ed net­work. The real­i­ty today is that what we com­mu­ni­cate online is medi­at­ed by com­pa­nies that own and oper­ate the Inter­net ser­vices we use. Social media in par­tic­u­lar have become, for an increas­ing num­ber of peo­ple, win­dows on real­i­ty. Whether, and in what ways, those win­dows might be dis­tort­ed — by cor­po­rate poli­cies or gov­ern­ment direc­tives — is thus a mat­ter of sig­nif­i­cant pub­lic impor­tance (but not always easy to dis­cern with the naked eye),” says Ron Deib­ert, Direc­tor, the Cit­i­zen Lab, Munk School of Glob­al Affairs, Uni­ver­si­ty of Toron­to.

The Cit­i­zen Lab, based at the Uni­ver­si­ty of Toronto’s Munk School of Glob­al Affairs, has exten­sive expe­ri­ence uncov­er­ing Inter­net cen­sor­ship prac­tices through net­work mea­sure­ment and reverse engi­neer­ing tech­niques.

For media inquiries, con­tact:

Dena Allen
Pub­lic Affairs & Engage­ment Munk School of Glob­al Affairs Uni­ver­si­ty of Toron­to Tele­phone: 416.946.0123
Mobile: 416.795.3902

Guide on Cit­ing in Media

Title: One App, Two Sys­tems: How WeChat uses one cen­sor­ship pol­i­cy in Chi­na and anoth­er inter­na­tion­al­ly

Pub­lished By: The Cit­i­zen Lab, Munk School of Glob­al Affairs, Uni­ver­si­ty of Toron­to,

Pub­li­ca­tion Date: 30 Novem­ber 2016