Florian Mierzejewski
Staff Engineer @ Qonto
Software engineer with 15+ YoE and a strong mobile background. I’ve worked in agencies and startups for widely different clients from various countries, on an even wider range of projects. From greenfield to enormous untested legacy codebases, I’ve seen horror and glory while repeatedly managing to have a positive impact. Eternal learner, you’ll always find me with a book, listening to a podcast, or at a local meetup to improve what I know or discover something I don’t. I aim to always write simple and readable code, apply best practices, share knowledge, pair program, and mentor with a good dose of empathy and compromise.
Stop Building the Whole App
When an engineer is working on a single feature, they only care about changing code, running it, and validating fast.
At Qonto, our app has 1k+ modules and 300+ features, yet the default workflow still forces engineers to build and install more than they need, so they spend minutes waiting and clicking around to reach the right screen.
That’s why we changed our approach: instead of building the full app, we generate DevApps, small per-feature apps that build fast, open the right screen, and let engineers validate changes with the same confidence as the main app.
In this talk, you’ll learn how we:
- Designed an architecture that builds only one feature and its dependencies
- Solved key challenges (DI, navigation, login, data)
- Prevented DevApps from breaking as the codebase evolves
- Built tooling engineers love (skip login, auto-fill forms, mock services)
- Measured and increased adoption and performance
Come learn how to build mini apps and get your feedback loop back.