Since you’re reading this, you’re likely in pursuit of an API that provides you with up-to-date currency rates.

Well, so were we mid-2019, when we added the currency-conversion feature to Kittysplit (a side business we are part of).

Who are we?

We’re a small software agency, called toy rocket science based in Berlin, Germany. Our customers include Deutsche Post, commercetools and the Berlin Philharmoniker. Besides client software development, we all have a knack for good software products and have built a lot of them together over the last years, some more successful some less and others never saw the spotlight.

Why another Currency Rates API?

The Competition

Back to Kittysplit mid-2019. We compared a few different APIs and integrated one of them. It worked well enough, but there were a couple things we didn’t like. First it was REST only, as was the entire competition. A secure connection was only provided for paid plans. Response times were often slow and some other annoyances.

Nevertheless we started integrating and using it, but kept in mind, that a currency rates / conversion API that meets all our demands would be a nice future side project for us.

Time for a side project

As 2019 was coming to an end and a bigger client project was just finished, we had some spare time for a side project.

The foreign exchange rate API topic came back to mind and seemed like a good fit. The size of the project was perfect for our time budget and the technologies we wanted to try out.

We started with the following broad goals:

  • A high quality API that could serve as a showcase for the work of toy rocket science
  • GraphQL API endpoint as first citizen, REST endpoint with equal care
  • Quality documentation and example code to ease integration
  • Secure connections for every user
  • Fast response times
  • CI pipeline and testing strategy from the start

Side project turned product

So we set out to build a Currency Rates API that meets our requirements. Development began on the side in October 2019 with an initially limited feature set to our specific needs, but we decided at one point, that we should go further. Over the first half of 2020 our little side project evolved a lot, so we eventually decided to take the next step and turn it into a full-fledged SAAS product to be offered to all in need of a Currency Rates API.

Naturally a product needs a name, we think SWOP is a good fit! We launched silently August 2020 and continue to improve v1.0.

As a small agency we built and helped building backend systems and APIs with our clients for years, but can rarely talk about them and never get into the details. So we hope SWOP is useful to you and/or gives you some insight how we as toy rocket science built APIs and software products.

But we merely started. We still have great plans on how to further improve our offering and will talk about that over the coming months.