DEV by Hookay
dev.hookay.eu · Engineering Notes

Building social software that knows as little as possible — and works anyway.

DEV is the engineering notebook of the teams building Hookay. We write about the craft of privacy-preserving product engineering: the patterns, the trade-offs, and the times a constraint made the product better. If RED is what we learn from attacking our systems, DEV is what we learn from building them.

// Security findings and post-mortems live at red.hookay.eu

Latest

Recent publications

How we build

Constraints we chose on purpose

Most engineering blogs describe what their teams may do. Ours is easier to explain by what we've ruled out — and why the product got better for it.

01

Privacy is a build constraint

Data minimization isn't reviewed in, it's designed in. If a feature needs data we don't want to hold, we redesign the feature. Every time, the result has been a more interesting product.

02

European stack, end to end

EU sovereignty shapes every dependency decision — from cloud to AI APIs to analytics. Constraint breeds invention: we've built things others outsource, and we write about what that costs and earns.

03

On-device or not at all

AI features have no server fallback. This is a harder engineering problem than calling an API, which is exactly why it's worth writing about.

04

Boring where it counts

We spend our novelty budget on privacy engineering and product. Everything else is proven, documented, replaceable technology — chosen so a small team can run it well.

Stack

What we build with

The public version — the same one in our job postings. Deep dives on individual choices appear as articles above.

Backend Kotlin · Spring Boot · PostgreSQL · NATS — services that are easy to reason about, queues that don't lose messages.
iOS SwiftUI · SwiftData · Apple Foundation Models — native first, offline-capable, intelligence on the device.
Android Jetpack Compose · Room · Gemini Nano (ML Kit) — full feature parity, same local-first architecture.
Platform Kubernetes · GitOps · EU infrastructure only — declarative everything, deployed from version control.
Geo H3 hexagonal indexing — the foundation of every location feature, and the reason we never store a coordinate.

// What you won't find here: our topology, our configurations, or anything that maps our attack surface. Same editorial rule as RED — lessons, not blueprints.

Join us

Build the app people don't delete

We're a small European team building social infrastructure for queer life — with privacy as the engineering brief, not the legal afterthought. If the articles above read like problems you want to own, we should talk.

// Remote within the EU · German or English working language · jobs@hookay.eu