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PassAndroid
(f-droid.org)
I actually used this for the first time last weekend (for a concert ticket). Worked well enough to display the QR code, although the labels were all sorts of messed up (although that might just have been the file itself).
Also started using it a few months back and hasn't let me down so far.
I've been a big fan of this when I had a cineworld membership. Worked like a charm!
F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.
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