The archive · Business Models · Strategic decision · 2015
Mondo opens a bank API before launch, and a beta user builds his own online banking
While Mondo was still in alpha it gave testers a real card and a public API — James Allison used both to build his own web banking client overnight.
Mondo
What it had to solve
Mondo, a UK challenger bank still in alpha, gave testers a bright pink prepaid MasterCard with instant purchase notifications, geotagged transactions and automatic categorisation — and exposed those rails through a public API, running its second developer hackathon in November 2015. Beta user James Allison, new to REST APIs, had spent ten days watching his own real transactions flow through that API.
How it works
In November 2015 Mondo, a UK challenger bank still in alpha and months from a full launch, was running its second developer hackathon. James Allison, a beta tester with a bright pink prepaid MasterCard, had spent ten days watching instant purchase notifications, geotagged transactions and automatic categorisation — first in Mondo's app, then through its public API — and the novelty had not worn off: this time the data was his.
The creative idea was visible from the outside: Mondo treated its API as part of the product before launch, and its alpha users as potential developers. Allison wanted a web client for balance, today's spend and transactions, so one evening he built it in Bootstrap and PHP — login, access token in the session, transactions on screen. When tokens expired after six hours he detected expiry by calling the accounts endpoint and checking whether an account number came back, then re-authenticated; he mimicked Mondo's Balance and Spend Today counters and started adding charts by category.
Posted as "My bank has an API so I built online banking", the demo drew 164 points and 108 comments on Hacker News, where people from Mondo, the Open Bank Project and Plaid joined a debate about regulation — PSD2 and the UK's Open Banking Working Group — and whether user-built banking was the future. Allison closed by looking forward to Mondo's full release, "where we'll all be able to see the full potential of API banking".
Why it lands
- Mondo shipped a documented public API before its full launch, so a customer could build on his own live data rather than a sandbox demo.
- The hackathon created the habit: Allison had already used the API there, and the six-hour token expiry forced him to solve a real session-management problem.
- The demo proved the platform idea in public — a customer produced a banking surface the bank had not built, months before Mondo fully launched.
- The write-up framed an evening project as a statement about API banking, which is why a Mondo employee and open-banking founders joined the discussion.
What it did
Posted as "My bank has an API so I built online banking", the finished demo drew 164 points and 108 comments on Hacker News, where people from Mondo and open-banking projects joined the thread to debate where bank APIs were heading — an early public proof that a customer could build his own banking UI before the bank had fully launched.
What you can take
Give platform users the real thing early: a live API with real data, plus an event that teaches them to use it, turns customers into product developers — and their demos become your marketing.
Since then
Allison kept extending the client with category charts and looked forward to Mondo's full release and its planned multi-account support. The Hacker News thread became a small time capsule of the late-2015 open-banking debate: a Mondo employee described the API as "a sneak peak of what's coming from potentially all banks in 3 or so years", pointing to the UK Open Banking Working Group, while founders of the Open Bank Project and Plaid used the thread to present their own approaches to bank data access.
Sources
- My bank has an API so I built online banking
- My bank has an API so I built online banking (Hacker News discussion)
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