Full-Stack Software Engineer
Janindu
Gayanga
Building scalable, real-time production systems across iGaming, Fintech & EdTech — currently building with AI & LLM APIs. 3 years+ delivering with Next.js, Node.js, Go & AWS.
Full-Stack Systems
End-to-end features from UI to cloud infrastructure
Real-Time Backends
WebSocket & Kafka pipelines for high-concurrency workloads
API & Microservices
Scalable REST / Go services with RBAC & OAuth 2.0
Cloud & DevOps
AWS deployments, Docker containerisation, CI/CD pipelines
About Me
Code built to
last
I'm Janindu Gayanga, a full-stack engineer with 3 years+ building production-grade systems — scalable REST APIs, microservices, and real-time WebSocket backends that handle real traffic.
At BotCalm, I ship across iGaming, Fintech, E-commerce & EdTech — with Next.js, Nest.js, Go & AWS in Agile teams. I've built payment gateway & crypto exchange integrations, and am actively building AI-integrated systems in my own time. Studied at SLTC Research University.
Expertise
Skills & Technologies
Frontend
Backend
Databases
Cloud & DevOps
Security & Auth
Also Working With
Career
Work Experience
From intern to software engineer — I've grown across iGaming, Fintech, E-commerce & EdTech, and am actively building AI-integrated systems. Always prioritising quality, performance, and continuous improvement.
B.Sc. (Hons) Software Engineering
Sri Lanka Technological Campus (SLTC)
2020 – 2024
July 2025 – Present
Software Engineer
BotCalm Private Limited · Sri Lanka
Architecting high-performance full-stack features with React / Next.js and Nest.js microservices on AWS. Building real-time iGaming & Fintech modules with WebSockets and Kafka for thousands of concurrent connections. Optimising cloud-native CI/CD pipelines and participating in rigorous Agile/Scrum code reviews.
August 2024 – June 2025
Associate Software Engineer
BotCalm Private Limited · Sri Lanka
Designed and deployed secure RESTful APIs and full-stack applications on AWS for four production projects across iGaming, Fintech, E-commerce, and Education. Integrated Crypto Exchange & Payment Gateway providers (Plaid, Coinbase Commerce), reducing per-integration time by 60%. Maintained high codebase integrity through structured code reviews.
March 2024 – November 2024
Software Engineer Intern
NEWNOP Private Limited · Sri Lanka
Delivered 5+ responsive web pages for the Lallaloi platform using Next.js and Tailwind CSS with AWS S3 asset management. Implemented systematic debugging protocols, contributing to a 30% reduction in reported UI defects.
March 2020 – March 2024
B.Sc. (Hons) Software Engineering
Sri Lanka Technological Campus (SLTC) · Padukka
Honours degree in Software Engineering. Award: CodeMania v2.0 (IEEE Computer Society SLTC) — Second Runners-Up. Coursera: Cloud Computing Applications (Cloud Systems and Infrastructure).
Portfolio
Featured Projects
Next.js · NestJS · Go
Enterprise iGaming Platform
Real-time gaming platform serving thousands of simultaneous users with 90+ Lighthouse scores and 40% faster page loads. Full PWA with offline support and i18n (RTL). Event-driven microservices architecture with WebSocket & Kafka backends scaled to 10,000+ concurrent connections, sub-100ms latency. Core microservices migrated from Node.js to Go for high throughput; hybrid MongoDB/PostgreSQL, RBAC, OAuth 2.0.
NestJS 10 · Next.js 14 · PostgreSQL
Nexora — Contact Centre CRM & Analytics
Production contact centre platform featuring dynamic schema-driven call logging and supervisor analytics. Call categories and capture fields are modelled entirely as data with immutable keys and soft-deletes in a JSONB details structure, ensuring historical audits remain 100% faithful. Features full-text search across records, role-based access control (Admin, Supervisor, Agent), and high-throughput query reporting.
NestJS · Next.js 14 · PostgreSQL
AskLK — Bilingual AI Assistant
White-label multi-tenant RAG assistant for Sri Lankan organisations — ask in Sinhala or English and receive grounded answers in that language with inline citations. Fuses vector search (pgvector 768d) with full-text search via Reciprocal Rank Fusion inside a single SQL query. Features four anti-hallucination layers and an embeddable 4.4KB gzipped Shadow DOM widget.
NestJS · Next.js 14 · PostgreSQL
QueueLK — Live Queue Management
Real-time queue display and mobile tracking for clinics, dispensaries and salons. Patients scan a door QR code to monitor their live place in line with zero app install required. Guarantees gap-free, duplicate-free token numbering under concurrency via SELECT FOR UPDATE row locks and transaction-level idempotency keys. Live updates streamed via Server-Sent Events (SSE) in Sinhala, Tamil, and English.
Next.js 14 · NestJS · Go
BookLK — Service Booking Marketplace
Open-source multi-vendor booking marketplace enabling service providers to manage availability while customers book live appointment slots. Features a 4-layer concurrency shield preventing double-bookings (idempotency key, Redis SET NX lock, SELECT FOR UPDATE inside serializable transactions, and database UNIQUE constraints). Real-time slot availability pushed via a dedicated Go WebSocket daemon with HMAC webhook reconciliation.
Electron · React · Node.js
Offline Retail POS System
Zero-latency offline desktop POS system engineered for high-volume retail. Features instant keystroke-filtered barcode scanning from any screen state, stacked 3-layer discount engines in integer-cent arithmetic, and barcode weighing scale integration. Silent 80mm thermal receipt printing, automated SQLite WAL database snapshots with USB mirroring, and machine-bound offline licensing.
Next.js · React · TypeScript
GC Property Dubai — Real Estate Platform
High-performance luxury real estate portal tailored for the Dubai and UAE property market. Features granular multi-criteria property search, interactive maps, dynamic media galleries, and automated lead capture pipelines. Built with media-heavy responsive architecture, image optimization, and advanced server-side rendering for optimal Core Web Vitals and international SEO.
Go · Binance API · DeepSeek AI
Autonomous Crypto Trading Bot
Autonomous 24/7 multi-coin trading system for Binance Futures, written in Go. Ranks the market's top movers by 24h volume and volatility to rebuild its watchlist hourly, combining DeepSeek for trade decisions, Gemini for news sentiment, and Fibonacci / Elliott Wave indicators. Built with strict risk controls, automated stop conditions, Telegram alert bots, and a live web dashboard.
Next.js · React · TypeScript
Hotel & Travel Booking Platforms
Full-stack hospitality and travel platforms powering direct room bookings, itinerary builders, and reservation workflows for Sri Lankan travel brands. Features transactional availability checks to eliminate booking conflicts, multi-currency pricing, and responsive marketing pages optimised with Next.js SSR/SSG for search engine indexing and rapid international visitor loading.
Get In Touch
Let's Connect
Open to full-time roles, freelance projects, or conversations about building something great. I'd love to hear from you.