I’m building a single Python-based gateway that will sit in front of ERPNext and Vercel, plus an extra module that handles RO, IT and Peppol invoicing rules. The idea is simple: clients will talk only to my gateway, receive one merged Swagger/OpenAPI spec, and never need to know the underlying services even exist. When a new developer (including myself as the designated admin) signs up through the gateway, the service must silently create the corresponding user in both ERPNext and Vercel by calling their official APIs. Key points you’ll tackle • Python backend (FastAPI or similar) that forwards requests to ERPNext and Vercel and returns a unified response set. • Runtime generation of a combined Swagger/OpenAPI document, covering every proxied route plus the custom RO/IT/Peppol invoice endpoints. • User registration flow that triggers background user creation in ERPNext and Vercel, assigning appropriate roles automatically. • PostgreSQL persistence for user accounts, API keys, audit logs and any invoice-related metadata. • Clean, version-controlled codebase with environment configuration ready for Vercel deployment. Deliverables 1. Fully-working gateway application with Docker setup. 2. PostgreSQL schema and migration scripts. 3. Complete OpenAPI file reflecting all merged routes. 4. README covering local dev, deployment to Vercel, and API usage samples. I’ll provide access tokens and test instances for ERPNext and Vercel. If you have experience with Peppol standards or European e-invoicing compliance, highlight that—otherwise I can supply the domain rules. Looking forward to keeping the conversation human and collaborative.