# Frontend Engineering > Selected Engineer ApS work demonstrating Frontend Engineering — the achievements that prove it. - [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/) - [Hardened the application with nonce‑based CSP, HSTS, SameSite cookies, least‑privilege database roles and server‑side entitlement re‑checks.](https://platform.engineer.company/portfolio/hardened-the-application-with-nonce-based-csp-hsts-77/) - [Built a layered automated test suite — 981 Go tests, 543 frontend and browser specs, 494 SQL behavioural tests — with mutation testing, property‑based tests and an accessibility gate.](https://platform.engineer.company/portfolio/built-a-layered-automated-test-suite-across-four-layers-94/) - [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/) - [Built a commit gate of 22 one‑line linters plus five that earn a paragraph, with no warning tier and no inline suppressions permitted, covering HTML, CSS, JavaScript, Python, YAML, Markdown, shell, links, spelling, secrets and typography.](https://platform.engineer.company/portfolio/built-a-22-linter-commit-gate-127/) - [Cut the site's browser‑driven quality gate from 1,636 seconds to 615 by scheduling its checks longest‑first through a worker pool bounded to four lanes, after measuring that alphabetical order cost 320 seconds against 224.](https://platform.engineer.company/portfolio/cut-the-visual-quality-gate-to-ten-minutes-128/) - [Mirrored the entire site as 777 Gemini documents and 777 Gopher documents off the same deployed tree, at zero bytes of change to the HTML.](https://platform.engineer.company/portfolio/mirrored-the-site-to-gemini-and-gopher-137/) - [Brought 10,242 lines of quality‑gate JavaScript under a formatter and a linter after establishing it was the largest body of code in the repository and the only one nothing read, fixing 13 findings and suppressing none.](https://platform.engineer.company/portfolio/brought-the-quality-gate-code-under-a-linter-143/) - [Stopped an application filling memory at 41 MB a second — a recorded 111 GB of compressed pages on a 36 GB machine — by bounding every event stream, subscribing by event type and putting a rate budget on logging, taking 610,996 log lines down to 1,411.](https://platform.engineer.company/portfolio/stopped-an-application-filling-memory-at-41mb-a-second-155/)