Backend Developer

Role summary Build the backend platform for a new web product: authentication and identity verification, wallet and payment integrations, domain APIs, real-time event delivery over WebSocket, metrics, and reporting. You will work in a team of three engineers on parallel workstreams. AI coding tools are welcome for scaffolding — *wallet, ledger, and payment webhook code requires human design and peer review. Responsibilities: Platform & architecture - Own or contribute to PostgreSQL schema (Prisma or TypeORM), migrations, and data modelling. - Design ledger-style wallet and settlement using decimal.js + NUMERIC — never floating-point. - Implement authentication: JWT/OAuth2, RBAC, 2FA hooks, session policy. - Define OpenAPI contracts and engineering standards (Jest, idempotency, error shapes). - Code-review gate on PRs touching payments, wallet, or realtime paths. Payments & identity - Build wallet service: balance, deposit, withdraw, history, statements. - Integrate payment gateways (e.g. Razorpay, PayU, Instamojo): checkout, webhooks, refunds, failure handling. - Integrate KYC/identity providers: document upload, verification status, webhooks. - Implement reconciliation jobs (BullMQ): gateway vs ledger tie-out. - SMS OTP and email verification (with DevOps). Realtime product & analytics - Build core domain APIs for multi-step user workflows and entity management. - Implement real-time updates via WebSocket (Socket.IO or NestJS Gateway) and Redis pub/sub. - Build metrics and profile services: aggregates, history, user-facing statistics. - Build reporting APIs: dashboard data, export hooks. - Coordinate event contracts with the frontend team. Cross-cutting - - - Write unit and integration tests; document webhook idempotency and replay behaviour. Wellversed with DevOps on DB, Redis, queues, and environment configuration. PCI-aware patterns: hosted checkout only; no raw card storage on application servers. Required qualifications - 5+ years professional backend development; 3+ years TypeScript + Node.js in production. - NestJS (or strong Express/Fastify background + readiness to work in NestJS). - PostgreSQL: schema design, transactions, migrations, indexing. - REST API design; validation; structured error handling. - JWT, OAuth2, RBAC implemented in production. At least one of the following demonstrated in prior work: - Fintech / wallet / ledger (idempotent webhooks, reconciliation), or - Realtime systems (WebSocket, Redis pub/sub), or - Technical leadership (schema ownership, code review, API contracts). Nice to have: - Indian payment gateways and KYC vendor APIs. - decimal.js / big.js for money; BullMQ; Prisma; Socket.IO. - High-traffic B2C or marketplace backends. - Comfort with AI-assisted development and strict review on financial code.