Full-Stack Developer for Recruiting SaaS Platform

We are looking for an experienced Senior Full-Stack Developer or a small professional development team to redesign and further develop an existing multi-tenant recruiting SaaS platform. The platform already has a working codebase and must not be rebuilt from scratch. Existing functions, data structures, and workflows must be reviewed and preserved. The project includes: * Complete UI and UX relaunch * Candidate, company, contact, project, and talent-pool management * German and English language support * Microsoft Outlook Add-in and Microsoft 365 integration * Email and calendar synchronization * Secure CV processing and irreversible candidate anonymization * Customer shortlists and protected profile-sharing links * AI-supported candidate matching and search * Sales pipeline, tasks, activities, and time tracking * Professional invoicing with ZUGFeRD support * Administration-area redesign * Server security, tenant isolation, and DDoS protection The developer should have strong experience with Next.js, TypeScript, backend development, databases, SaaS architecture, Microsoft Graph, OAuth, document processing, and application security. A detailed German and English development specification is available and will be provided to suitable candidates. Please include examples of similar SaaS, ATS, CRM, or recruiting platforms you have developed, your proposed approach, availability, estimated timeline, and preferred milestone structure.