People in Beijing can now use QR codes as tickets across all subway lines, after 6 million passengers tried it during a trial over 20 days.

They need to download an app called Ruubypay and connect it with either their bank account, Alipay, or JD Finance account. A QR code will be generated as you open the app, and by putting your phone near the QR code reader, it will let you pass through almost as fast as using an actual ticket.

A passenger getting through subway gate by scanning a QR code. (Picture: CCTV)

It could save a lot of time for passengers who forget to bring a metro card and have to queue up to buy a ticket.

"At certain subway stations, it may take a rather long time to get a ticket. Sometimes, it can be up to twenty minutes. This way, it's so much easier," CCTV quotes a passenger as saying.

Beijing’s subway already lets people pay on phones with NFC, which is how most mobile payment services (like Apple Pay) work in the rest of the world. But 70% of China’s internet users pay with their phones -- and it’s almost always done through QR codes.

Beijing's subway also says they’ll start trial of payment by facial recognition later this year.