I’m Jonas — a backend engineer currently based in Kawasaki, Japan (just outside Tokyo). I’m originally from Germany, and somehow ended up here, which I consider a net positive.
What I do
I work on backend systems — identity, authentication, high-throughput APIs, that sort of thing. I like systems that have to be correct under load, and I’ve spent a fair amount of time with Kotlin, Rust, Cassandra, Kafka, and Kubernetes in anger rather than just in tutorials.
I care about the internals of things. Not just “it works” but why it works and what happens when it doesn’t.
Outside work
Homelab — I run a small but unreasonably complicated home server setup: Proxmox on a Lenovo M720q, a k3s cluster, ArgoCD, Traefik, Gitea with Actions for CI/CD. It’s the kind of thing that’s objectively unnecessary and absolutely worth it.
Hardware projects — I design the occasional PCB. A button box, an AC controller/sensor, and a LED Tokyo subway map that I am slowly making less embarrassing. KiCad, soldering, the works.
Japanese — studying toward N3. It’s going fine. Slowly.
Cats — Heidi and Hugo. Heidi believes the laptop keyboard is her territory. Hugo is more reserved about it.
Get in touch
Email is the most reliable: jonas@jwolff.it