# Security & Access Management > Selected work demonstrating this service. - [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://software.engineer.company/portfolio/designed-an-organization-context-switching-system-with-client-59/) - [Built email as a platform capability — three providers with failover, delivery webhooks, send and delivery logging, templating and campaigns — behind a startup check that will not boot without one.](https://software.engineer.company/portfolio/built-email-as-a-platform-capability-with-failover-62/) - [Hardened the application with nonce‑based CSP, HSTS, SameSite cookies, least‑privilege database roles and server‑side entitlement re‑checks.](https://software.engineer.company/portfolio/hardened-the-application-with-nonce-based-csp-hsts-77/) - [Built the payments and entitlements layer — Stripe alongside Apple and Google in‑app purchase — gating the directory, search and export through an 11‑table access model checked on the server.](https://software.engineer.company/portfolio/built-the-payments-and-entitlements-layer-96/) - [Built fail‑closed abuse controls — 22 Redis‑backed rate limiters, Cloudflare Turnstile, request idempotency and an origin lock — so the platform sheds bots and floods instead of trusting its callers.](https://software.engineer.company/portfolio/built-fail-closed-abuse-controls-and-rate-limiting-100/) - [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://software.engineer.company/portfolio/built-company-ownership-claims-end-to-end-103/) - [Reached the half of the messaging core the application had never used — backup transfer, disappearing messages, message editing and resending, verified invitations, proxies and encryption policy — driving every test against the real library with no mocks.](https://software.engineer.company/portfolio/reached-the-unused-half-of-the-messaging-core-161/)