The hackathon this app was a part of doesn't mention developer-friendly banks: https://getmondo.co.uk/blog/2015/11/22/mondohack/
I'm left to assume these are private APIs. I would love to play around with APIs similarly, but don't want to depend on privatized APIs.
You can find our API documentation here: https://getmondo.co.uk/docs
The APIs will be publicly available to developers and account holders. We've only just started rolling out our first cards, though, so we're not on boarding many third party developers at the moment.
If you'd like to play around with the API, send an email to developers@getmondo.co.uk and we'll see what we can do :)
Sending an email (although I'm based in US, if that matters).
Not that you have it good, but holy he'll did starting a not-bank end up being a can of worms in the US.
From their director of API banking, "With API banking we aim to deliver a set of services that allow our customers to interact with the bank securely, programmatically, at high speed and with little (or no) manual intervention." https://www.svb.com/Blogs/Dan_Kimerling/Our_Mission_for_API_...
http://blog.ycombinator.com/standard-treasury-yc-s13-joins-s...
This is because online account opening for banks is a very hard problem, and anyone with a bank charter basically can't use the closed loop trick that other services are using to provide money movement and storage without a charter.
Once you are past account opening, it's more about tech politics. No major US bank has publicly pushed an Oauth gateway, for example. But this is more about risk and the politics of contracts with financial aggregators than anything else. You can find hints of these murky waters in the articles surrounding the recent dust up between Chase and Intuit.
Authentication was incredibly easy and they handled security questions very gracefully in my opinion. I was able to build a pretty good Simple Goals clone with a weekend's worth of work.
I haven't used their Plaid Auth product yet.