Sebastian Fastner

Leading up to the first production deployment, my main focus was making the platform reliable to test, ship, and restore. Staging and production now share one deployment workflow, new environments are set up by script, and CI runs leaner with sharded test suites and shared caches. Restore tests check that a recovered database is actually usable, database passwords no longer end up in server logs, and uploaded PDFs are sanitized. On the product side, I work on the business modules, for example the whistleblowing system from the database to the React interface.

I took on work across the application: access rules based on professional group and prescription status, search including the IDENTA drug identification, product pages, and structured data and tracking for search engines and advertising. Targeted regression tests and a shared TypeScript and lint check secure these fixes.

React Router 7, TypeScript, and Convex form the technical foundation. The application integrates Google Calendar via OAuth as well as CalDAV-compatible calendars such as iCloud and Fastmail, generates iCal feeds, sends customizable email templates through customer-owned SMTP servers, and protects sensitive credentials through encryption. Better Auth with Pocket ID, Bunny.net Static Hosting with Edge Middleware, security headers, rate limits, health checks, and an extensive Vitest-/Playwright-oriented test base support operations and ongoing development.

The product core separates an open, local i18n foundation from a commercial translation and control layer. Delta translations, terminology and protected terms, context enrichment, QA reports, targeted retries, and traceable PO metadata form the central product functionality. The website was built with React Router 7, Vanilla Extract, Lingui, and self-hosted Convex; newsletter flows, a preference center, double opt-in, unsubscribe mechanics, Relanto email delivery, Pocket ID admin authentication, and a Convex-based API key and pipeline structure support the product architecture.

A plugin system for GraphQL resolvers and mutations in the Go backend formed the core of the solution. Translations were integrated transparently into the service APIs and cached in Redis. Temporal workflows with queues, workers, retry mechanisms, throttling, and rate limiting controlled processing. Because plain-text user content could not be stored in the queue for security reasons, I developed a performant encryption system for Temporal. I also built CLI and operations tools for job management, testing new workflows, and retrying failed translations. The backend was restructured and decoupled, making it easier to maintain and understand.

I introduced continuous deployment for faster, reliable releases and a shared web/mobile architecture. Jest and React Testing Library covered core UI behavior across varying regulatory and localization requirements.

Next.js, React, and Styled Components formed the frontend; Apollo GraphQL unified the backend services. AWS, Kubernetes, and Vault supported secure continuous deployment, while GraphQL query tests protected releases.

After a Vue.js/MobX prototype, I ported the frontend to React and TypeScript, built an enterprise React component library, and owned the Webpack, Babel, and ESLint tooling. Spring Boot connected investment and CRM systems; Keycloak handled OpenID/OAuth. REST services and CI/CD ran on Microsoft Azure.