Inside Qonto

Building our own banking platform from scratch

November 14, 2019 by Lucie Casamitjana

Thaddée is a Core Banking Expert at Qonto. So you must be wondering what a Core Banking (System) is? That’s lucky — he’ll be able to tell you a bit more about his work at Qonto and the technical challenges we face!

After a few years at Captain Train (which has since become Trainline), he was attracted to the Qonto project and joined the team in 2017 to take part in new challenges with a common purpose: to modernize the banking experience for businesses!

Qonto, the beginnings

“I wanted to discover new challenges. To me, the banking industry needed to take big steps to offer a modern experience to businesses. Alex, Steve and Gabriel convinced me that they had a long-term vision, an eye for detail, a customer focus, and were above all ready to put the hard work in.”

In Qonto’s early days, Thaddée’s roles were varied and he worked with several technical stacks at the same time.

“When I arrived at Qonto, I was developing the front-end (the graphic interface) and the back-end (data storage and the operation processing logic)For example, I added VAT amount selection to transactions.”

Towards a technical challenge

When the time came to develop our own banking platform, Thaddée naturally focused on the back-end when he joined the project.And what a project!In technical jargon, we call it:the “Core Banking System”.This is a back-end system that enables monetary flows to move from one account to another.But who better placed than Thaddée to give you more details on the topic?

“Core Banking enables us to protect our customers’ accounts, while following the obligations that are part of our approval from the ACPR.We maintain a database, the accounting ledger, to explain the origin and destination of all fund movements.This database scrutinizes accounts to ensure that everything is in order.It reconciles accounts held by our partners, and makes the necessary transfers to protect customers’ funds (which is called confinement in the jargon)”.

“Our Core Banking system enables us to execute our customers and their partners’ transactions.We are connected to major interbanking networks such as SEPA, Mastercard and the French check network.Each one has its own set of rules.Our servers respond to card payments, apply direct debits, send transfers and guarantee that the information users read when they log in to their Qonto accounts is transmitted properly.”

A complementary back-end team

This new banking platform is one of the most exciting stages in Qonto’s life!It means gaining independence to offer an experience that meets our clients’ needs as closely as possible, and continuing to build the service that businesses deserve.

To attack this new challenge, Qonto has surrounded itself with technical stars like Thaddée, with varied and complementary profiles, who have been able to make it all possible!France, Ukraine, Great Britain, China, Belgium, Tunisia, Canada, Brazil, Venezuela… in short, the Qonto back-end team already has a few stamps on its passport.

“The team was built throughout 2018 and grew to reach ten people.Recruitment was not easy, but luckily we have a wonderful HR team that works relentlessly to help us recruit the best people!We have selected people of varied backgrounds, each with complementary expertise to bring to the whole team.We are also surrounded by banking professionals to put all the cards in our favor.”

Furthermore, the first 100% Qonto product, which is available on our banking platform (or Core Banking System for those who love banking jargon) will soon be available!We’ll tell you more in this article.

Please see our openings if you also want to help us meet our technical challenges!

Let’s talk tech 🤖

His inspirations...

  • Fabrice Bellard - “I’m impressed by his genius. He produces very ambitious systems that reach his goals because he’s not afraid to dig deep.” 
  • Chris Lattner - “A very unique person. I admire his ability to coordinate broad open-source efforts despite the complexity of the topics he addresses.” 
  • Ian Hickson - “He is fantastic in his pragmatic management of standardization processes which have led to the boom in Web applications in the past decade.” 

A few reading recommendations...

  • “I like the classics...” - Structure and Interpretation of Computer Programs 
  • “...and those that are more recent” - Site Reliability Engineering 
  • Articles by Jepsen “who studies discrepancies between distributed database promises and the results of their home-made tests.” 
  • In terms of modern start-ups - L’obsession de service client by Jonathan Lefèvre. 
  • Out of a love for yesterday’s visionaries - Mother of all Demos by Douglas Engelbart   
  • For the subtle details that make all the difference - 99% invisible  


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