Senior Software Engineer · EDC Group · Copenhagen
I design, build, and operate production systems across mobile (Expo/React Native), web (Next.js), and backend (.NET/NestJS/Postgres). Typed contracts, deterministic CI, and clean data models are non-negotiable.
- 7 VS Code extensions with 1,000+ installs
- Founder/operator on multiple SaaS products
- Proven delivery on mobile + .NET stacks at enterprise scale
- Feature flags, observability, zero-downtime migrations by default
Danish driving theory exam platform. iOS live, Android next.
Stack: React Native (Expo), TypeScript, .NET API, Postgres, Supabase, App Store CI/CD
Links: iOS App · Compare Driving Schools
AI-assisted translation workflow with real source-of-truth and missing-locale guards.
Stack: Next.js 16, TypeScript, .NET on Railway, Postgres, pnpm packages for Expo/Next
Link: phraseflow-web.vercel.app
Space/desk/asset lifecycle with AI assistance.
Stack: Next.js 16, .NET, OpenAI, Railway
Link: useworkspace.dk
Built 7 VS Code extensions (selected):
- ErrorClipper — Copy errors with code context; AI-ready snippets (~453 installs)
- Aether – Sublime Code Theme — Focused, contrast-correct theme (~192)
- Git Branch Manager — One-click cleanup of merged branches (~152)
- Azure DevOps Code Companion — Boards and repos in-editor (~104)
- IntelliSense Number Suggestions — Smart numeric hints (~91)
- ClickUp Code Companion — Ship tasks from VS Code (~88)
- TODO Debt Manager — Visualize and burn down tech debt (~32)
All extensions: https://marketplace.visualstudio.com/publishers/YonasValentinMougaardKristensen
- Typed boundaries or no boundaries — shared DTOs/Zod schemas, contract tests, generated clients.
- Monolith first, modular later — bounded contexts enforced by folder and ownership, not hope.
- Observability from day one — logs, metrics, traces, budget alarms, and user-visible SLOs.
- Migrations are products — progressive rollouts, backfills, and kill-switches.
- DX compounds — reproducible dev env, seed data, fast feedback, preview deploys.
- AI assists, humans decide — codegen for glue, human review for architecture.
- [ ] Contract tests updated (DTOs/Zod) and generated clients bumped
- [ ] Zero-downtime: write → read → deprecate path applied to migrations
- [ ] Telemetry added (metric + trace + log) and dashboard link posted
- [ ] Security review: RLS/claims/roles; secrets via env or vault; no PII in logs
- [ ] Rollout plan with flags and rollback command included
Migration Playbook (excerpt)
1) Additive schema only. Deploy write paths behind a flag.
2) Dual-write and validate. Backfill idempotently with chunked jobs.
3) Flip reads to new source behind a flag. Monitor error budgets.
4) Remove dual-write. Drop legacy only after cold period with snapshots.
⸻
Architecture Defaults
• API: .NET/NestJS, CQRS where it pays off, MediatR/handlers for cross-cutting concerns
• Data: Postgres, Prisma/EF Core, RLS on external-facing contexts, audit trails
• Frontends: Next.js 16 and Expo, strict TypeScript, feature flags, e2e happy-path tests
• AI: OpenAI for summarization/assistance; no black-box decisions in core flows
• Ops: Railway/Vercel, GitHub Actions, canary + auto-rollback, environment-scoped secrets
• Analytics: PostHog/Umami, event contracts, server-side ingestion preferred
⸻
Proof of Work
• Scaled Workr (student job marketplace) to ~80,000 users over 9 years
• Shipped multiple SaaS products and a live App Store app as operator and engineer
• 7 VS Code extensions installed by 1,000+ developers
• Delivery track record across mobile + .NET in a regulated, data-sensitive domain
⸻
Day Job
Senior Software Engineer @ EDC Group
Shipping React Native apps and .NET backends for real estate workflows. Focus: reliability, clean data, measurable outcomes.
⸻
Stack
Mobile: React Native (Expo), TypeScript
Web: Next.js 16, React, TypeScript
Backend: .NET, NestJS, Node.js
Data: PostgreSQL, Supabase, Prisma
AI: OpenAI API
Ops: Railway, Vercel, App Store Connect, GitHub Actions
Currently deepening .NET/NestJS architecture and database scaling. Frontend specialist who ships backends that hold up.
⸻
Build Signals
⸻
Contact
Email: [email protected]
LinkedIn: /in/yonas-valentin
Support: https://buymeacoffee.com/yonasvalentin