Deutsche Bahn's tickets suck a bit. You're stuck with a choice between a PDF (to be printed onto paper – remember paper?) or their not-very-good mobile app. Most airlines and coach companies hand out their tickets and boarding passes in user-friendly de-facto standard formats like Apple Wallet or just a simple 2D barcode to be shown in your email app – but not Deutsche Bahn.
Deutsche Bahn has shown little incentive to change that – so we'll have to do it ourselves.
Fahrkar.de lets users forward their tickets by email, parses their data and turns it into a nice, offline-ready HTML-based ticket.
The code is a bit of an undocumented mess (yes, I'm parsing the Aztec codes out of the PDF by hand; yes, I'm including the zxing JAR files in the repository). It was cobbled together within 24 sleeples hours at Deutsche Bahn's Hackathon in June 2016.
Thanks to rumpeltux for his previous work on DB's Online Tickets on which much of my parsing is based.