Janindu
Gayanga

Expertise

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Portfolio

Featured Projects

• TypeScript · NestJS · Next.js 15

  AskLK: Bilingual AI Assistant with RAG, Agents and MCP

  An assistant a Sri Lankan clinic, school or company can point at its own documents. I wanted it to say "I don't know" rather than guess, so retrieval is hybrid (pgvector plus Postgres full-text, merged with Reciprocal Rank Fusion), every answer cites its sources, the agent waits for a human before any write, and an MCP server lets Claude Code search the same documents.

  • TypeScript
  • NestJS
  • Next.js 15
  • React 19
  • PostgreSQL
  • pgvector
  • Prisma
  • Redis
  AskLK case studyAskLK showcase on GitHubFull source available on request.

• TypeScript · Next.js 14 · NestJS

  BookLK: Event-Driven Service Booking Marketplace

  Customers book time slots with salons, clinics and repair shops, vendors get paid out, and the platform keeps a commission. It is four services plus a job worker, joined by a transactional outbox to Kafka, with a Go WebSocket service for live updates. Payments run on Stripe test mode and the PayHere sandbox, and they are reconciled every night.

  • TypeScript
  • Next.js 14
  • NestJS
  • Go
  • PostgreSQL
  • Redis
  • Kafka (Redpanda)
  • MongoDB
  BookLK case studyBookLK showcase on GitHubFull source available on request.

• TypeScript · NestJS · Next.js 14

  QueueLK: Real-Time Queue Management for Clinics

  A screen on the waiting-room wall and a page on the patient's phone, for Sri Lankan dispensaries, clinics and salons. Patients scan a QR code and see how many people are ahead of them, with nothing to install. The hard part was keeping token numbers gap-free and unique when everyone scans at once.

  • TypeScript
  • NestJS
  • Next.js 14
  • React Native (Expo)
  • PostgreSQL
  • Prisma
  • Redis
  • Server-Sent Events
  QueueLK case studyQueueLK showcase on GitHubFull source available on request.

• TypeScript · Next.js 15 · NestJS 11

  ApplyWise: CV Tailoring Where Every Line Cites a Fact

  A web app, not launched yet, that breaks a CV into small editable facts, matches them to a job description, and writes a tailored CV and cover letter where each line cites the facts behind it. A verifier (rules first, then an LLM judge) strips anything unsupported. There is also a free ATS checker, an application tracker and a Chrome extension.

  • TypeScript
  • Next.js 15
  • NestJS 11
  • Prisma
  • PostgreSQL
  • pgvector
  • Redis
  • BullMQ
  ApplyWise case studyApplyWise showcase on GitHubFull source available on request.

• Go · Next.js · React

  iGaming Platform: Go Microservices, Payments and Compliance

  A real-money gaming platform with live wallets, crypto and card deposits, withdrawals, bonuses and an operator admin panel. I'm a core member of the team moving it from a Node.js/MongoDB monolith to 20 Go services behind an API gateway. My own pieces are the notification/WebSocket service, the NOWPayments crypto integration, the vault service, the Vesant and GeoComply compliance gates, and the support chat.

  • Go
  • Next.js
  • React
  • TypeScript
  • WebSockets
  • Kafka
  • PostgreSQL
  • Redis
  iGaming Platform case studyProduction · code under NDA

More work

• Nexora: Contact Centre CRM & Analytics

  Contact centre platform in production for a client, with schema-driven call logging, supervisor analytics, full-text search and three roles (Admin, Supervisor, Agent). Call categories and their fields are stored as data. A field's key can't change once created, and records are deactivated rather than deleted, so old calls still read correctly in an audit.

  NestJS · Next.js 14 · PostgreSQL · Prisma · Redis · Production client work

  Nexora architecture notes on GitHub

• Offline Retail POS System

  Offline desktop POS running in a real shop. The barcode scanner is read as a keyboard and told apart from typing by keystroke timing. It handles weighing-scale barcodes, keeps money in integer cents and prints receipts through the Windows driver. SQLite runs in WAL mode, and a backup is taken after a bill (at most once a minute) and checked by reopening it. USB mirroring is optional. Licensing is tied to the machine.

  Electron · React · Node.js · SQLite · Client product

• GC Property: Real Estate Listings

  Property listings site for Sri Lanka (gcproperty.lk). Filters live in the URL path, so "3 bedrooms in Colombo" is a real page that can rank. Listings come from a Strapi CMS on PostgreSQL, with media on S3-compatible storage.

  Next.js · React · Strapi · PostgreSQL · Client work

• Crypto Trading Bot

  Personal Go bot on Binance USDT-M futures. Every hour it rebuilds a six-coin watchlist from volume and volatility. DeepSeek returns a strict-JSON trade decision, Gemini adds a news-sentiment read, and about fifteen Go risk gates decide whether the order is allowed. One position at a time, with Telegram alerts and a small dashboard.

  Go · Binance API · DeepSeek · Gemini · MongoDB · Personal project

• Hotel & Travel Sites

  Two client sites. The hotel site is a React SPA whose reservation flow posts to the hotel's own booking API. The travel agency site is a static Next.js build with no third-party runtime dependencies.

  React · Next.js · TypeScript · Tailwind CSS · Client work