Project Profile
Sebastian Fastner
Senior React & TypeScript Developer
Available immediately (as of August 2026) · Full-time
Engagement via Sebastian Software GmbH
Remote-first; occasional on-site work throughout Germany, Austria, Switzerland, and the Benelux. More distant locations by arrangement.
Sebastian Software GmbH
Technical Focus
- React
- TypeScript
- Next.js
- Node.js
- GraphQL
- Testing
- CI/CD
Direct Contact
- Contact
- s.fastner@sebastian-software.de · +49 176 32042696
- Location
- Mainz, Germany
- Languages
- German and English
Project Profile · 1 / 4
Senior React & TypeScript Developer
Project Experience · Platforms & Commerce
DWS / MorgenFund · Investment Management Platform
Senior Frontend Architect · 10/2020 – 07/2024
Long-term development of an international investment management platform as Senior Frontend Architect.
- Implemented the migration to Azure and a continuous deployment strategy.
- Ported a React dashboard to React Native and rolled it out to additional European and Asian markets.
React, React Native, TypeScript, Azure, Continuous Deployment, and Node.js
Witt-Gruppe (Otto Group) · Multi-Brand E-Commerce Platforms
Senior Frontend Architect · 04/2019 – 09/2020
Led the frontend rebuild for the Witt Group within the Otto Group.
- Established the technical foundation for 17 multi-brand online shops across international markets.
- Built a Next.js/React frontend, an Apollo GraphQL layer, and automated test infrastructure.
Next.js, React, Apollo GraphQL, Contentful, AWS, Kubernetes, and Node.js
Project Profile · 2 / 4
Senior React & TypeScript Developer
Project Experience · Fintech & Internationalization
DWS (Deutsche Bank) · Robo-Advisor Investment Platform
Senior Frontend Architect · 04/2016 – 03/2019
Built the WISE white-label investment platform for multiple European and Asian countries.
- Delivered from sales prototype through to a production white-label robo-advisor.
- Took ownership of a React/TypeScript component library and the complete frontend tooling stack.
React, TypeScript, Vue.js, Spring Boot, Keycloak, DocuSign, and Node.js
Regrello · AI-Powered Internationalization
Senior Technology Consultant · 10/2024 – 09/2025
Internationalized an enterprise SaaS platform using TypeScript, Go, GraphQL, and AI-assisted translation.
- Developed a GraphQL plugin system, LLM-powered translations, and encrypted Temporal workflows for six target languages.
- A one-off on-site assignment in the US demonstrates willingness to travel internationally.
Go, GraphQL, Redis, Temporal, Google Gemini, TypeScript, and Node.js
Project Profile · 3 / 4
Senior React & TypeScript Developer
Recent Hands-on Products
Terminaro · Product by Sebastian Software GmbH · SaaS · Appointment Booking System
Product Engineer · 01/2026 – 08/2026
Multilingual appointment scheduling system with a public booking page and integrated administration.
- Implemented public booking, administration, calendar integration, email delivery, and secure deployments.
- Used React Router, TypeScript, Convex, and automated tests as an end-to-end product stack.
React Router, Convex, TypeScript, Better Auth, CalDAV, and Bunny
Palamedes · Product by Sebastian Software GmbH · Dev Tools · AI-Powered Localization Platform
Product Architect · 10/2025 – 06/2026
Developer-first platform for AI-assisted localization within Git and release workflows.
- Designed and implemented a CLI-first workflow, translation pipeline, QA reports, and terminology features.
- Delivered the website, newsletter backend, authentication, and API and pipeline infrastructure.
AI Applications, Localization, React Router, Convex, TypeScript, Lingui, and Relanto
Additional Experience
- 2016Deutsche Telekom · Senior Application Architect
- 2015–2016Jako-o · Lead Application Architect
- 2015Deutsche Telekom · Lead Application Architect
- 2014Suzuki Deutschland · FullStack UI Architect
- 2014Deutsche Bank · Frontend Developer
- 2010–2013Deutsche Telekom / Tolino‑Allianz · JavaScript Developer
Education, Languages & Contact
- Degree
- Diplom-Informatiker (FH) – German diploma in computer science
- Contact
- s.fastner@sebastian-software.de · +49 176 32042696
- Location
- Mainz, Germany
- Languages
- German and English
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