There are two QR codes and the gate only likes one of them

No ticket machine, no card, no queue. You hold your phone against a scanner and the gate opens. When it works it is the best public transport experience anywhere, and when it does not you are standing in a barrier with a queue forming behind you wondering what you did.

Two codes, and they are not interchangeable

Alipay has a transport code that works in a lot of cities. Most cities also have their own metro app with its own code. Where both work, use whichever. Where only the city app works, the Alipay code gets refused with no explanation at all, and that is the confused thirty seconds.

Staying in one city for a while: install its metro app. Moving around a lot: the Alipay code covers the most ground for the least faff.

The mistake almost everyone makes first

Opening the payment code instead of the transport code. They look nearly identical and they do entirely different jobs. The gate wants the transport one and will not tell you that.

How to actually scan

Flat against the reader, close, not waved at it from above. And turn your screen brightness up, because a dim screen in a sunlit station entrance fails again and again for no visible reason.

Scan on the way out too

Metro fares are by distance, so you tap in and tap out. Leave without tapping out and the journey stays open, and the next one may be refused until it is sorted.

Buses take the same codes on boarding, and the fare is usually flat, so there is nothing to do when you get off.

When the gate says no

• Wrong code. See above. It is usually this.
• Screen too dim.
• Card declined behind the scenes, which looks identical to everything else going wrong.
• Fall back to a single-journey ticket from the machine, which takes cash or a payment QR.

Questions people ask

Can I use Alipay to ride the metro in China?

In many cities yes, through the transport code inside Alipay. Some cities require their own metro app instead.

Do I need to scan out on the Chinese metro?

Yes. Fares are calculated by distance, so you scan both entering and leaving.

What is the difference between the payment code and the transport code?

The payment code pays a merchant. The transport code is a separate pass tied to the transit system. Gates only accept the transport code.

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