Damruwan Weerasinghe
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Full-stack software engineer specializing in multi-tenant SaaS products for retail and service businesses. Built and shipped a suite of B2B systems — POS & mini-ERP, HR/payroll, and gym CRM — on a shared Node.js/TypeScript + React architecture with subscription billing, role-based access control, and real-time/IoT integrations.
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Years Exp
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Products Built
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Major Projects
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Companies
Experience
Feb 2025 – Present Colombo, Sri Lanka
- Architected a reusable multi-tenant SaaS platform reused across 8+ products, significantly cutting new-product setup time.
- Built a POS & mini-ERP with inventory, multi-warehouse stock, purchasing/suppliers, sales, manufacturing BOM, serial-number tracking, coupons, and PDF/Excel reporting.
- Delivered an HR & payroll system covering employee records, configurable pay items, automated payroll runs, attendance, leave management, and holiday calendars.
- Developed a workforce/facility-management ERP with site staffing, attendance-driven payroll, client invoicing, leave and vehicle tracking.
- Created a gym CRM with membership packages, class scheduling, attendance, and biometric door-access control via HikConnect over MQTT.
- Engineered backend foundations: JWT + Redis, RBAC, OTP, rate limiting, BullMQ, WebSocket, AWS S3, Swagger (NestJS).
- Built React/Next.js frontends with Redux Toolkit, Tailwind/Ant Design, Chart.js, Sentry and PWA/offline support.
Junior Software Engineer
@ Spins & Spaces (Pvt) Ltd Nov 2022 – Apr 2024 Horana, Sri Lanka
- Designed a shareholder event-logging feature to track interactions for event correspondence.
- Built an AGM resolution-voting system to manage resolutions and collect votes securely.
- Developed full-stack features using C# .NET and Oracle Database.
Skills
Languages
TypeScriptJavaScriptPythonC#HTML5CSS3
Backend
Node.jsExpressNestJSREST APIsSequelizeBullMQSocket.ioMQTTRedis
Databases
MySQL/MariaDBPostgreSQLMongoDBOracle
Cloud & Tooling
AWS S3FirebaseDockerCI/CDGitMulti-tenant SaaS
Projects
SeaSavers
Mobile app promoting marine conservation with gamified cleanup competitions and educational blogs.
Expo, Appwrite
Retaily
Fashion retail platform with personalized recommendations via collaborative and content-based filtering.
Next.js, PostgreSQL, ML
QueryMate
Chatbot resolving customer queries with conversational AI and vector-search API integrations.
Next.js, MongoDB, OpenAI API, Pinecone
Education
B.Sc. (Hons) in Information Technology
Software Engineering
Sri Lanka Institute of Information Technology·2019 – 2025
CGPA: 3.19
Certifications
MongoDB Node.js Developer Path
MongoDB