What does Stripe use for storage on backend?
api, database, stripe-payments
Solution
I don't work at stripe but take a lot of interest in their work. Some research has revealed that the keys (well the charge object keys which you are referring to at least) are randomly generated by their application code. See this Quora post from Patrick Collison.
In relation to databases: Judging by this blog post, I would estimate that they primarily use PostgreSQL with a growing amount of MongoDB usage. For instance, their open source Gaps tool uses MongoDB for data persistence. Sorry I can't post the link here, limited to 2 links per post for now. You can find it on github though.
Problem
I notice Stripe uses a database that formats keys/IDs as `ch_15aCcp2eZvKYlo2CYmE3Fy2h` where "ch_" seems to be a prefix of the table name, or the type of Object that is being stored. What database does this style of ids? Might be custom but I've seen other API providers use similar style ids. This is purely for my own curiosity.