DojoBooking started from a real problem: accommodation platforms either handled the booking experience well or the financial layer well — rarely both. Property owners needed more than a listing tool; they needed a full financial infrastructure they could trust. So I set out to build the backend for a dual-sided marketplace that would treat financial operations with the same rigor you would expect from a fintech product.

The architecture is built on NestJS with TypeScript, using a domain-driven module structure that keeps each business concern — authentication, KYC, wallets, payments, communications — cleanly separated. One of my earliest decisions was to use RSA asymmetric keys for JWT signing rather than HMAC, combined with a rotating session token stored in the database. This meant we got stateless auth for most reads, but could still invalidate sessions instantly on new logins without maintaining a token blocklist. Every login rotates the DB token, so old JWTs fail validation even if they have not expired.

The most technically interesting part of this project was the financial infrastructure. The owner wallet system computes balances dynamically from a transaction ledger — summing credits and subtracting debits — rather than maintaining a mutable balance column. This is a deliberate choice: financial data correctness matters more than read performance, and it gives us a complete audit trail. Withdrawal requests run inside TypeORM database transactions, creating a wallet transaction record and a withdrawal record atomically.

On the infrastructure side, I used Bull queues backed by Redis to handle all async side effects — welcome emails, verification links, wallet event notifications — entirely outside the HTTP request cycle. The communication layer is built around a pluggable provider factory pattern where the active email provider is read from a settings table at runtime, enabling live provider switching without a redeployment.