From legacy architecture to 10M+ downloads: how an embedded ITGRATE engineer rebuilt Chefkoch's Android app — and leveled up the team that owns it

A senior engineer, embedded in the client's own team, rebuilt a flagship German app's architecture from the ground up — shipped measurable gains, and left the in-house team stronger than they found it. This is how ITGRATE's dedicated model works in practice.

The client

Chefkoch is one of Germany's most-used digital products — a household name with one of the largest cooking and recipe communities in the DACH region. Its Android app sits in the hands of millions of users every week. When an app operates at that scale, "rewrite the architecture" stops being a technical preference and becomes a business risk: every change touches real users, real reviews, and real revenue.

That's exactly the kind of work ITGRATE was brought in to do — not as an outside vendor handed a spec, but as a senior engineer embedded directly inside Chefkoch's own development team.

The challenge

The Android app had grown on an aging foundation: a heavy RxJava-based MVVM setup with UI built in legacy XML layouts. It worked — but it had reached the point where every new feature cost more than the last, the codebase was hard to reason about, and modern Android tooling couldn't be adopted without untangling years of accumulated architecture.

For a product at Chefkoch's scale, the danger isn't writing new code. It's migrating a live, high-traffic app to a modern foundation without breaking the experience for millions of existing users — and doing it while the product keeps shipping. That demands someone senior enough to make architecture decisions and disciplined enough to make them safely.

Why embedded, not outsourced

This is the distinction that matters for any team considering external engineering support. ITGRATE didn't take the work away to a black box and return a finished product months later. A senior engineer joined Chefkoch's team and worked inside it — same standups, same codebase, same standards — but delivered from ITGRATE's side with German-market management wrapped around it.

That model is the whole point: you get senior capacity in weeks instead of a three-month German hiring cycle, the person is genuinely part of your team, and the work product belongs to you the entire way through. It's the same model ITGRATE runs for Dedicated Product Teams — proven here at the individual senior level, scaled up with more engineers when scope demands.

What we did

Over a sustained, multi-stage engagement, the app was migrated from its legacy foundation to a modern, maintainable architecture:

• Re-architected the codebase from heavy RxJava/MVVM with XML layouts to a clean Redux pattern in Kotlin, applying SOLID principles and established design patterns rather than bolting on quick fixes.
• Rebuilt the UI layer in Jetpack Compose, bringing the app onto Android's modern declarative UI toolkit and out of legacy XML.
• Brought the app to full GDPR compliance — non-negotiable for a German product handling millions of users' data.
• Delivered all of this on a live, high-traffic app, migrating incrementally so users never paid for the modernization happening underneath them.

The result wasn't just cleaner code. It was an app that could finally adopt modern Android libraries, ship features faster, and be maintained without fighting its own foundation.

Beyond the code: the team got stronger

This is what separates an embedded engineer from a contractor who disappears when the ticket closes. Throughout the engagement, ITGRATE's engineer actively upskilled Chefkoch's in-house developers — running them through Kotlin Coroutines, the latest Jetpack libraries, and the reasoning behind the new architecture.

The deliverable was never just a rebuilt app. It was a Chefkoch team that came out the other side more capable than before — able to own and extend the new architecture themselves. For any company weighing external engineering help, that's the real test: does the partner make you dependent, or does it make you stronger? Here, demonstrably, the latter.

Why they kept us

The engagement began with a defined scope. It didn't end there. What started as a focused modernization mandate turned into a long-term relationship, because the work earned it — the client extended the engagement well beyond its original plan to keep that senior capability inside the team. Sticking around long enough to be asked to stay is, quietly, the strongest endorsement an engineering partner can get.

In the client's words

"It is an absolute pleasure to design and implement high-quality solutions together. He likes to pass on his technical knowledge to educate the team — on topics like Kotlin Coroutines and the latest Jetpack libraries — to push the whole team forward. His independent, meticulous way of working, combined with his ability to support teammates, greatly boosted the project's progress. I hope we get the chance to work together again."— Tobias Würschinger, Senior Android Developer, Chefkoch GmbH

(Original endorsement in German; available on request.)

The results

App rating

Grew to 4.7★

Downloads

10M+

Delivery speed

+40%

Quality

+27%

Compliance

100% GDPR-compliant

In-house team

Upskilled in modern Android (Kotlin Coroutines, Jetpack Compose)

What this means for your team

If you're a funded DACH startup or scale-up with a roadmap your current team can't ship fast enough, this is the model: a senior engineer — or a small dedicated team — embedded in your workflow, productive in under two weeks instead of a three-month hiring cycle, managed to German standards and delivered from our Vietnam side. You get the capacity. You keep the code, the standards, and a team that's better for having worked with us.

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ITGRATE GmbH · Munich, Germany + Ho Chi Minh City, Vietnam