Flink logo

Grocery Shopping Online Made Easy

The platform reaches up to 10 million users available in over 60 cities across four countries.

Flink cover

The company and product

Flink reaches up to 10 million customers

Flink is an online grocery shopping application based in Germany with a bold, consumer-focused mission: to deliver orders within minutes at supermarket prices. It's possible due to the smooth cooperation of multiple applications addressing each step of the delivery process, including mobile apps for the end-users and the e-commerce system, for drivers, pickers, and the ERP system.

Flink attracted investors at a record pace and is already available in over 60 cities across four countries. Flink now reaches up to 10 million customers.

Client’s feedback

Flink logo

Ahmed Khalil

Head of Engineering at Flink

Ahmed Khalil

Superb cooperation

Product and business management from Monterail are amazing. They make sure that we are happy as a client and they are willing to go as far as possible to make sure that the clients’ requirements are met. It was a superb cooperation.

Scope and Highlights










The Challenge

Making the backend production-ready.

Flink (“quick” in German) began as a startup at the end of 2020 and raised $240 million in less than six months. Interest soared during the pandemic, and further funding helped them expand their operations to the Netherlands, France, and Austria.

Their offer is composed of a series of connected apps for different user types, such as customers, riders, and warehouse workers. Flink structures teams narrowly around each app or even specific features. It’s a dynamic setup where staff might be relocated often, to the benefit of efficient implementation.

Early on, they moved the app from React Native to Kotlin & Swift on the frontend, but needed assistance making the backend production-ready. Speed was crucial, and outsourcing was the answer, especially considering their accelerated growth.

Flink and Monterail partnered up in March 2021, and initially, Monterail was set to provide Golang and testing expertise.

Local talent shortage.
Very dynamic team structure.
Pressure from a competitive market.
Local talent shortage.
Very dynamic team structure.
Pressure from a competitive market.
flink mobile application

The Process

Expert backend code review, code migration, and breaking down monoliths.

Starting from an expert backend code review of Flink apps, we created a list of suggestions and then started implementing them right away. The QAs worked on both the backend and the frontend, providing everything from ad hoc regression to smoke testing, and ensuring the migration would happen without a hitch.

Beyond migration, Monterail worked on multiple features across the ecosystem. Some highlights include a desktop webshop, checkout and payment functionalities, order location tracking and post-order user experience, user authentication, and authorization.

The scope also included systems for back-office operations, covering a warehouse employees app, a dashboard for managing specific orders, and inventory management.

Data migration was an especially interesting challenge. We developed a custom API to transfer data from Saleor to Commerce Tools, affecting several applications in the ecosystem. All under the hood, so end users don’t feel any change.

Along the journey, we helped strategically break down monoliths, such as the checkout and cart systems, into microservices. This separation ensured not only scalability but also work efficiency, as now different developers can contribute more closely with less risk of conflict.

This is how we made it happen:

  • Quick and precise initial code review in Go.

  • The Monterail team grew from two to eleven, following business needs.

  • Pro-active and smooth communication across the board.

flink app

Team’s voice

Monterail logo

Magdalena Barańska

Project Manager

Magdalena Barańska

Fast while maintaining high quality

We joined at an early stage, so it was crucial that our initial code review was done quickly while maintaining high quality.

The Outcome

No roadblocks to accelerated growth.

Thanks to using the Go language for the project, developers could easily switch teams and work on different applications without a problem. The team, consisting of up to eleven developers and QA engineers, joined different Flink rockets which enabled fast-paced development and accommodated the dynamic needs of the project.

The partnership gave Flink access to a valuable and flexible pool of first-rate Go developers, QA engineers, and other specialists in a core stage of fast expansion.

With this solid foundation built, our partner is able to more easily include features and scale their efforts across different locations. For example, adding a warehouse to the system began as a complex technical task and now doesn’t require an engineer. It’s easier to add cities and even countries, leaving no roadblocks to accelerated growth.

The success of this project hinged on the following factors:

  • The apps enjoy scalable growth due to Go expertise.

  • Flink had access to developers as soon as the business needed them.

  • Different teams have an easy time connecting and integrating.

Grzegorz Hajdukiewicz | Chief Delivery Officer

I'm here to gather your requirements, answer all your questions, and push your idea into development as fast as possible.

Grzegorz Hajdukiewicz | Chief Delivery Officer

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