Fullstack Engineer - Mid Level - Actions Team

We're looking for a Fullstack Engineer to join our Actions team in building the core infrastructure that powers our plugin platform. You'll create the UI components, integration layers, and security mechanisms that enable our customers to extend the platform with custom integrations while maintaining safety and flexibility across our 1,500+ customer base. This is essential infrastructure work that shapes how our customers scale their integrations.

• Building a UI component library that generated apps can assemble from, turning components like payslip views and approval flows into maintained, reusable pieces instead of regenerated artifacts
• Creating the connection layer between generated apps and customer source systems—HR platforms, time-tracking and scheduling systems, and a long tail of vendors with thin or undocumented APIs
• Defining extension points (widgets, menus, sidebars) so plugins declare where they surface and what they connect to in a single, clean configuration
• Designing and implementing a cross-integration authentication solution that lets customers run multiple integrations without forcing employees to log in repeatedly
• Shipping plugins on the platform yourself, staying a consumer of what we build so we catch gaps early

• Strong knowledge of React and TypeScript for frontend work Java/Kotlin or Go an TypeScript experience for backend services
• Real experience integrating third-party APIs, especially the challenging ones—inconsistent auth, partial documentation, legacy and on-prem systems
• Deep understanding of multi-tenancy security and data isolation; you care about scope checks and preventing cross-tenant leaks
• Good judgment about what to standardize and what to leave flexible—drawing that line in the right place is central to this role
• You are comfortable with edge and serverless runtimes like Cloudflare Workers
• You have built a plugin system, SDK, or developer platform before
• Developed a design system or component library that other teams depended on
• Real-world experience with OAuth and enterprise SSO
• Experience treating AI code generation as a product surface, not just a personal tool

• Competitive Compensation - we offer attractive salary packages including LTIP (unit-based Long Term Incentive Plan)
• Flexibility - we offer flexible working time models and the option of hybrid work, and support this with a yearly flex work allowance of €1560
• Recharge - with 31 vacation days annually (incl. one floating holiday), plus pro rata fully paid Fridays off during August
• Support - we offer offering a company pension scheme
• Volunteers Day - you'll get one day off per year for supporting a social project