Willem Stuursma-Ruwen

Willem ist Senior Developer bei Mollie und verantwortlich für alle Development-Aktivitäten bei Mollie. Er arbeitet gerne am Backend: API Design, Sicherheit und Performance. Zuletzt beschäftigt er sich mit der kontinuierlichen Verbesserung des Development-Prozesses.

Join Mollie at the PHPBenelux Conference 2017

Join Mollie at the PHPBenelux Conference 2017

Mollie has been the sponsor of the Dutch PHP Conference for two years now. We have since become active in the Belgian market as well and would like to bring ourselves to the attention of local developers. We regularly sponsor meet-ups, user groups and conferences. This allows us to do something for all those developers who have chosen Mollie or implemented our API.

We are therefore pleased to announce that we will be the sponsor of the PHPBenelux Conference 2017. The annual PHPBenelux Conference is a two-day event for PHP developers from Belgium, the Netherlands and Luxembourg. The event is held in the Antwerp Hotel Ter Elst, the 27th and 28th of January. Tickets are almost sold out, so be quick! 

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Several of the members of our Development Team will attend both days of the conference. If you’re going to be there and would like to meet our developers, please come talk to us! You will recognize us from our Mollie shirts.

Vacancies at Mollie

We’re always looking for new colleagues. If you’d like to know more or meet up, get in touch for a cup of coffee at our offices. Interested in how we work? Check out our development blog!

An interview with Thijs, developer at Mollie

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.


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?

API changes May—August 2016

August 2016

July 2016

  • Added the ability to create mandates through the API (if enabled on your account). This is especially useful when pre-existing mandates can be used instead of having to get a new mandate from the consumer.
  • Added the description parameter to the create payment refund endpoint. Use this parameter to add a description, which we will pass to the consumer when possible.
  • Added consumer details for the Belfius Direct Net payment when retrieving a payment.
  • Updated the payment method icons in list methods.
  • Changed the minimum for Bancontact to €0.02. You can use this minimum for setting upfirst recurring payments. If you want to use this minimum for regular payments, please contact us to enable this on your account.

June 2016

May 2016

  • It is now possible for consumers to change the language on our hosted payment pages. The locale selected by your customer will be stored in the payments resource's locale property.
  • Added API key access to refunds top level endpoint. Use this endpoint to retrieve all refunds on the payment profile the API key is linked with.
  • Added mandate detail cardExpiryDate to credit card mandates.
  • Added OAuth2 parameters where needed and improved documentation for Issuers, Methods, OAuth, Payments and Refunds.
  • Added new user guide Recurring payments to explain how to get started with Mollie Recurring.
  • Added recurringType field to Payments API to support first and recurring payments.
  • Added new Customers Mandates API v1/customers/*/mandates that allows an application to find out whether a customer has valid accounts or cards that can be charged with recurring payments.
Previous entry: API changes January—April 2016.