Multi-Tenant Staffing SaaS Platform Dev (RBAC, Ledger, API) – Agency of 30-40 Needed

We are looking for an established software development agency (ideally with 30–40 employees on staff, to ensure sufficient capacity, redundancy, and continuity) to build a multi-tenant SaaS platform for the staffing and flexible-labor industry (similar to a "temp agency" or "gig staffing" business model, common in Europe, where a staffing company places workers with client businesses and manages the pay, invoicing, and commissions in between). The platform connects six different types of users, each with their own dashboard and workflow: a platform administrator who manages the overall system, tenants, and billing; an account manager ("sales rep") who manages client accounts and recruiters and earns a running balance based on approved hours; a recruiter who sources candidates through a unique referral link and earns commission as candidates move through a hiring pipeline; a client company ("employer") who posts jobs, invites staff, and approves submitted hours; a worker ("employee") who logs hours and views pay/roster information; and a job seeker ("applicant") who browses vacancies and applies. The core business logic revolves around hours worked by a placed worker being submitted, approved by the client company, and then automatically flowing through a calculation/rate engine that updates a financial ledger — crediting the account manager and recruiter with their respective commissions in near real time. A working demo/prototype of this flow already exists, and we are looking for a partner to turn it into a production-ready, scalable platform. Core Features: Role-based access control (RBAC) supporting multiple roles and permission levels Multi-tenant architecture (multiple client companies/organizations on one platform, with proper data isolation between tenants) Status/workflow engines for processes such as job applications and recruitment pipelines A rate engine to calculate hourly wages, margins, and commissions A financial ledger tracking balances, payouts, and accrued commissions Self-billing / automated invoicing Timesheet submission with an approval workflow (worker → client company) Notification system (in-app / email) Feature flags for phased rollout of functionality GDPR compliance, including data export capabilities for end users Job queues for background processing (e.g. calculations, notifications) Audit logging, admin impersonation, and manual override capabilities System health monitoring dashboard A public API (JSON format) allowing external parties (e.g. client companies, partners, or internal apps) to access platform data and functionality, including documentation, authentication (e.g. API keys/OAuth), and rate limiting Required Skills/Technologies: Frontend: React, TypeScript, modern component architecture, responsive design Backend: Node.js (or equivalent), with experience building complex authorization models (RBAC) and multi-tenant systems Experience designing and building public REST/JSON APIs, including API documentation (e.g. OpenAPI/Swagger), versioning, authentication, and rate limiting Database: PostgreSQL (or similar relational database), with experience in financial/ledger data modeling Experience with payment processing, invoicing, or payroll systems is a strong plus Message queues/background job processing (e.g. Redis, BullMQ, or similar) Knowledge of GDPR compliance in software design Experience with SaaS architecture and scalable, secure cloud infrastructure Strong testing/QA practices, given the financial and compliance-sensitive nature of the platform Clear communication in English (Dutch is a plus, but not required) What We're Looking For in a Partner: An established development agency with approximately 30–40 employees on staff, ensuring the team has enough in-house expertise across frontend, backend, QA, DevOps, and project management Proven experience with similarly complex, multi-role SaaS platforms (preferably in HR-tech, staffing, or fintech) Experience building public APIs for third-party integrations References/portfolio of past projects involving RBAC, multi-tenancy, and/or financial processing Willingness to commit to a long-term partnership (ongoing development and maintenance after launch) Process: We're happy to share a working demo/prototype for reference once we're in discussion. Please respond with your relevant experience, team size, and an estimated timeline and cost for Phase 1.