Freelance Backend • Clean Architecture// 2025• backend
Smile Care Dental API
Decoupled Billing & Worker Pipeline Engine
Freelance backend developed from 15 May to 3 Jun. Modular REST API in Node.js and TypeScript applying Clean Architecture with decoupled repositories, transactional billing on PostgreSQL, BullMQ/Redis worker pipelines, and an OpenAPI specification drafted with AI from Postman-tested endpoints.
OPINIONATED ARCHITECTURAL DECISION
Decoupled domain repositories with centralized dependency injection and composition root so billing calculation rules never touch database drivers.
WHAT I GOT WRONG & LESSONS LEARNED
Puppeteer headless PDF rendering initially ran on the HTTP request cycle, introducing 3–4 second request latencies until moved to an async BullMQ/Redis worker.
How I built this & what it delivers
Freelance backend project engineered from 15 May to 3 Jun applying Clean Architecture with decoupled repositories.
Automated billing engine on PostgreSQL transactions that generates dynamic PDF invoices via headless Puppeteer and Mailgen.
Designed a resilient BullMQ/Redis worker system for async email and invoice delivery with exponential backoffs.
Drafted OpenAPI specification with AI from endpoints tested and validated in Postman [TODO: endpoint count, line count].
// TECH ARSENAL
TypeScriptNode.jsExpress.jsPostgreSQLRedisBullMQPuppeteerOpenAPI 3.0
// PERFORMANCE & IMPACT
Clean Architecture • PostgreSQL Transactions • OpenAPI Drafted via Postman
Audited for production reliability, memory efficiency, and execution safety.