I’m building a ticket-based travel platform and need an experienced NestJS/Node.js developer to own the entire backend. The core of the job is to design and code a robust booking engine, connect it to external services, and expose clean, well-documented REST/GraphQL endpoints for the web and mobile apps that will sit on top. What has to plug in • Payment gateways, travel service providers, and user authentication services all need first-class, fault-tolerant integrations. I already have partner documentation for each service; your job is to wire them up, handle retries/timeouts, and log everything clearly. Booking workflow The platform must perform Real-time availability check before every purchase, send Booking confirmation notifications (email + optional SMS), and support full/partial Cancellation and refund processing that syncs with the relevant provider and returns funds through the original payment gateway. Access model Three distinct roles—Admin, Travel Agent, and Customer—will interact with the system. Please follow RBAC best practices and keep the policies configurable. Tech expectations • Node.js 18+ with NestJS • PostgreSQL (TypeORM or Prisma) • Redis for queues/caching • Jest unit tests and Postman/Swagger docs • Docker-based dev environment Deliverables 1. Modular NestJS codebase with environment-based configs 2. Integration layers for each external service, fully test-covered 3. Booking-workflow service with state machine or equivalent logic 4. RBAC middleware and seed scripts for the three roles 5. API documentation and a brief hand-over guide Acceptance criteria All automated tests pass in CI, API docs generate without errors, and a live demo on my staging server shows a full booking, cancellation, and refund cycle end-to-end. If you’ve built transactional platforms, especially in travel or e-commerce, I’d love to see a quick note on your most relevant project and a link to its repo or demo.