Knip App


This is a specialized app for the conductor on the train. The request is to validate that a mobile payment app will help the train conductor to deliver a more pleasurable journey to the travelers on the train, in case of not having a ticket.

This product is a newly developed product using Lean prototyping.


2018/2019, Secondment at NS on behalf of Luminis. They needed specific senior engineering skills on a development team at NS at the start of 2018, so that’s when I joined the team.

I’m part of a team doing cutting-egde agile, lean and devops software developments (as seen from a perspective of this large, semi-government organisation).
The team took on a mission to prove business concepts using fast iterations and tight coupling with end-users and the business. ‘Spiek’, is one of those business concepts.

This product was nominated ‘IT innovation of 2019’ at the NS, and finished second.

My part

I took part in the creative process, called ‘design sprint’. For 5 days we discussed with all involved parties the needed functionality. (Business, designers, UX, developers, Conducters).

This creative process included: business interviews, group priority sessions, group design sessions, end-user interviews, group decision sessions.

Because of the financial and personal information involved, we needed to be more cautious with our POC approach. We helped NS shape their rules to allow for business POC’s but at the same time deliver a secure and reliable product.

The product consists of an app, an backend-API with storage, and a website. The concept is that the train conductor uses the app to create a fine and then shows a QR code. This QR is a ABN Tikkie code that enables the user to use an external payment provider. After payment, the user is then redirected to our website and receives a valid ticket. Also the train conductor is notified of the completed payment.

I did the research into the ABN Tikkie coupling and designed the application architecture, the solution architecture in the NS landscape was provided by the architects. As the lead developer I oversaw the technical requirements, and of course I did build a lot of the back-end coding.

I really enjoyed making this app using the POC / MVP / Lean prototyping / value driven approach. The NS invited us to show our innovative product on 2 events, so here is a picture of me on one of those events.

Related stuff

Random order, tooling used

  • Azure: WebJobs / AI / ARM / Monitoring / CosmosDB
  • Xamarin MVVM
  • Angular 6 Website
  • .Net Core API REST using JSON
  • Integration with ABN Tikkie, using their API with JWT signing
  • AppCenter Metrics
  • Azure Devops
  • GIT sourcecontrolC# .Net Core
  • Continues Integration, Continues Deployment (VSTS Build / Xamarin Build / AppCenter UI testing / Release pipeline)
  • Testing (Unit testing, SpecFlow Xamarin UI tests using AppCenter, Postman integration testing)
  • SCRUM (Workflow, Stand-up, Refinings, Planning, Retrospectives, continues improvement, team maturity)
  • Lean prototyping, value driven development