An interview with Thijs, developer at Mollie

During interviews with developers we are often asked: what does an average working day look like for a developer at Mollie? To publicly answer that question, we’ve interviewed Thijs, who has been a developer at Mollie for about a year now.

Thijs, how did you start at Mollie?

During my studies at the University of Amsterdam, I had the option to take a two month internship for study credits. At my previous job, I had implemented Mollie as a payment service provider. Impressed with their API, documentation and work culture, I decided to apply for an internship.

During the internship I worked on adding support for gift cards to the Mollie API. I also did an internal research project on error rates and on how they impact Mollie. After my internship, Mollie extended me an offer for a position as a developer.

What did you learn during your internship?

For the most part, my study Computer Sciences focuses on topics like compiler design, sorting algorithms, data structures and a lot of math. All very interesting subjects, but a far cry from working on a live application that processes API requests each and every second of the day. At Mollie, I learned how to work as part of a team. I learned where to to apply object oriented design patterns, and where not to. I learned to test my code properly to validate my implementations. I learned to create and improve products that people use on a daily basis. Working on an actual product and growing the product is much more inspiring than the theoretical topics of my studies.

After my internship, I’ve worked on various things at Mollie – important updates like adding a fallback connection to a secondary iDEAL acquirer, and working on our open source API clients. I’ve worked on smaller changes as well, like allowing our customers to add descriptions to refunds, or improving the verification of VAT numbers.

Can you tell us a bit about the project you are currently working on?

At the moment, I am part of the Payments team. We’re in the process of adding a new payment method to improve our proposition for our Belgian customers. In recent weeks I’ve been working on making sure we charge the correct fees for the new product, as well as adding unit tests to ensure my changes work as intended. I am also working on the payment method’s reconciliation – the process where we match incoming transactions on our bank statements to the payments in our back office. We are getting more and more transactions on our bank accounts, so to ensure optimal performance, I’ve refactored our statement handler system to support input streams (using PHP’s yield functionality, among other things).

What are some activities that are part of your daily routine?

Usually I come in around half past nine. I’ll start coding on a smaller issue, or review a colleague’s code, until everyone’s in for our daily stand up. The remainder of the day I spend coding, reviewing, or brainstorming with the team on how we should tackle current issues.

Occasionally, we have team meetings like a sprint planning or a retrospective. Yesterday, I participated in a conference call with one of our suppliers. Around noon, we’ll have lunch at the office, which is prepared by our own chef. When it’s sunny outside, we like to spend some time on our office balcony as well.

What are some things you like working as a developer at Mollie?

Mollie has a team of developers who are all just as interested in software development as I am, which is very different from my previous job. There is lots of tooling available, such as pre-configured virtual machines for development, an extensive test suite, a continuous integration environment, and guides on how to set up debugging or profiling. We go to conferences as well. In June, the development department went to the Dutch PHP Conference, which was really informative.

Mollie is growing really quickly as well, and it’s cool to be a part of that.

Conclusion

We hope this gives you some insight in what working at Mollie as a developer entails. If you would like to know more, why not drop by for a cup of coffee?