# Full‑Stack Development > Selected Engineer ApS work demonstrating Full‑Stack Development — the achievements that prove it. - [Architected, developed, implemented, supported infrastructure, data processing, and the map application for 2 years non‑stop without any weekends, holidays, or vacations, 10–14 hours a day.](https://platform.engineer.company/portfolio/architected-developed-implemented-supported-infrastructure-data-processing-and-55/) - [Designed an organization context‑switching system with client localStorage and server‑side cookie mirroring, letting users act as managed organizations while enforcing least‑privilege authorization.](https://platform.engineer.company/portfolio/designed-an-organization-context-switching-system-with-client-59/) - [Built company ownership claims end to end — a user claims a company, an administrator adjudicates, and an approval rewrites the authorization graph that decides who is allowed to edit what.](https://platform.engineer.company/portfolio/built-company-ownership-claims-end-to-end-103/)