Alipay was a lifesaver
We used Alipay for our trip to Beijing and it worked great. You can set it up before you leave with credit card (used mastercard, amex doesn’t yet work). Do not set up the Touristcard, you don’t need it and it crashed on me. Once you have it set up: with scan, you can scan a merchants QR code and make a payment. Most of the time merchants scan you’re QR code. You generate one with the Pay/Receive button. Worked perfect. The third button is Transport. You can sign up (2-3 clicks) and you can get a QR code for metro (and bus and train - but didn’t use this). In the metro scan your QR code when you enter and when you leave the metro. The other great mini apps: DIDI Travel, for a taxi ride. It’s like an uber. Sometimes you’ll have to give (make a note) the last 4 digits of you phone number. Other app we used was Hello Ride, to use the blue city bikes. Same concept, scan when you start and end you’re ride. Make sure to return you’re bike in a parking area (easy to recognize because other bikes will be standing there). Also the translation button works will. There’s also a currency converter. Alipay was all I used, except for MAPS.ME and Apple Maps for navigation. One big watch out. Our credit card had a maximum of 15 transactions per day (for the account). That’s pretty limiting if you take the subway / bikes. We learned the hard way (we couldn’t pay our dinner one evening) and after that kept track of our transactions and ensured to always have some cash.