I recently released an open-source plugin for WordPress that adds a payment gateway to WooCommerce. There are other Stripe plugins for WooCommerce but one is $79 and the other one was lacking some features that I thought were necessary. Striper was the only open-source plugin that I could find and I decided I would work on improving that plugin and sending a pull request and calling it a day.
The problem with that thought process is that I got carried away. Striper and the WooThemes Stripe Gateway both save a Stripe customer for each credit card used. I decided that a better method would be to save a single customer in Stripe and attach multiple cards to that customer. That of course lead to a pretty big increase of complexity, but it worked out and Stripe for WooCommerce came into existence.