

A flexible Ruby Passbook Library - lgleason
https://github.com/frozon/passbook

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tazjin
I built one in Haskell at my old employer as well that works pretty smoothly
(the whole pkpass format is implemented on type level):
<https://github.com/tazjin/hs-pkpass>

Unfortunately the tool built around it never made it into production,
marketing cancelled the project :(

