App Developer (Flutter)

At DeWarmte, we make smart, affordable heat pumps that help homes move away from gas. We design the hardware, software and services ourselves, so the quality of our software directly shapes how well our products work in people's homes.

We're growing fast, and both apps need to grow with us. That's why we're looking for an App Developer (Flutter) to build and improve our two Flutter apps. Homeowners use the customer app to control their heat pump. Installers and service engineers use the employee app to install and maintain heat pumps in the field.

You'll spend most of your time writing code: improving quality and reliability and shipping features to iOS and Android. Your work has a direct effect on comfort at home and on how efficiently our installation and service teams work.

AI tools are already part of how we build software. We use them where they help us move faster, but we do not lower the bar: anything we ship still needs to be secure, maintainable and correct. You'll help us get better at both.

• The Hague; Utrecht
• Full time
• Hybrid
• Software
• €4K – €6K per month

Why this role matters

Build reliable, intuitive apps that give customers confident control of their heat pump and help our installation and service teams do great work in the field.

You'll join the team behind two apps used every day by customers, installers and service engineers. You'll get to know them deeply, keep them reliable and improve them as DeWarmte grows. Just as important: you'll help make sure knowledge and ownership are shared across the team.

What you'll do

Develop the DeWarmte apps

• Build the features homeowners and installers to use and control heat pumps
• Ensure that the DeWarmte apps stand out in the market with regards to usability functionality and innovation.
• Make sure the app holds up in real-world conditions, like a basement with poor connectivity.

Build a strong app platform

• Work directly in the production Dart/Flutter codebases for iOS and Android.
• Design, build, test and release new features, from first sketch to the App Store and Google Play.
• Evolve app architecture, state management and shared components across both apps.
• Work with our backend developers on clean, well-documented APIs.
• Improve automated testing, CI/CD, crash reporting, analytics and release practices.
• Diagnose and fix issues that span the apps, our Django backend and devices in the field.

Build with AI

• Use AI tools to support design, coding, testing, reviews and documentation.
• Help the team improve its AI workflows, shared context and quality checks.
• Try new tools, keep what works and share what you learn.
• Hold AI-assisted code to the same standards as any other production code.

Share ownership

• Turn implicit knowledge into clear documentation, tooling and repeatable engineering practices.
• Write code that other engineers can easily understand, test and safely change.
• Take part in code reviews and technical decision-making.

Work across the company

This role reaches beyond app development. You'll work with colleagues in product, backend, hardware, controls, installation and service—and listen closely to customers—to solve today's issues without compromising the apps for tomorrow.

What success looks like

In your first few months

• You understand both apps, how they connect to our backend and heat pumps, and where the risks are.
• You can independently build, debug and release changes to both apps through the team's review and release practices.
• The most important technical debt and quality issues are visible and prioritised.

As the role develops

• New features ship predictably, safely and with good test coverage.
• Customers trust the app to control their heat pump: crash rates go down and app store ratings go up.
• Thanks to the employee app, installations and service visits are faster and have fewer errors.
• The team uses AI tools confidently and responsibly in its day-to-day work.
• Both apps are understood and maintained by more than one person.

Who we're looking for

• Solid hands-on experience building and shipping production mobile apps with Flutter and Dart.
• Experience releasing and maintaining apps on both the App Store and Google Play.
• A solid grasp of app architecture and state management (e.g. Riverpod, Bloc or Provider).
• Experience integrating REST APIs, authentication and push notifications.
• A track record of taking functionality from design through implementation, testing and release to real-world use.
• Strong engineering fundamentals: version control, automated testing, CI/CD, crash reporting and performance monitoring.
• You use AI coding tools in practice and understand both their value and their limits.
• A feel for user experience and a knack for making complex information simple.
• The ability to bring clarity to an environment where systems and processes are still taking shape.

Experience with native iOS or Android development, offline-first apps, connected devices such as Bluetooth or Wi-Fi provisioning, IoT, energy or HVAC is useful, but not essential. What matters most is that you can learn a complex physical product and take responsibility from idea to release.

How you work

• You fix urgent problems without letting short-term workarounds become long-term architecture.
• You care about the details users notice, and the ones they don't.
• You're curious about new AI tools, try them quickly and share what works.
• You explain technical topics clearly to people from any background.
• You balance shipping today with the investments needed to scale tomorrow.
• You share knowledge by default and care about what the team can own together.

What we offer

• A role with direct impact on the apps customers use at home and our teams use in the field.
• The chance to shape both the app platform and the experience around it.
• Room to improve how we use AI tools across the software team.
• A gross monthly salary of [€4,500 – €6,000], based on full-time employment.
• 27 vacation days and 8% holiday allowance.
• The chance to share in DeWarmte's growth through our Stock Appreciation Rights (SAR) programme.
• An ambitious, collaborative team and real responsibility from day one.
• Daily lunch at the office.
• A laptop, access to the AI tools we use and everything else you need to do your best work.
• Regular team activities, including our annual Beach Day and Winter Trip.
• Plenty of room to grow, develop yourself and make a lasting impact.

Interested?

Want to build the apps that customers and colleagues rely on every day? We'd like to meet you.