Projects

Improve Digital's demand-side platform, giving advertisers a direct, efficient path to premium supply worldwide.

• Azerion's ad server handles billions of requests a day (owned by another team).
• My team owns ad configuration, deal management, reporting and security, where request counts are lower but data volumes are very large.

A multi-tenant Retrieval-Augmented Generation platform built as Spring microservices.

• Flow: Organizations upload versioned documents into topics. A transactional outbox + RabbitMQ pipeline parses, chunks and embeds them into PostgreSQL/pgvector. Users chat with a specific topic version and get grounded answers with citations, behind JWT auth and role-based access.
• Retrieval: hybrid search (vector + PostgreSQL full-text), fused with Reciprocal Rank Fusion; semantic conversation memory; token usage tracking.
• Services: gateway, config, user, document, ingestion, chat, db-migration.
• Backend: Java 25, Spring Boot 4.1, Spring AI 2.0 (OpenAI starter, RAG, PDF document reader), Spring Security + JJWT (access/refresh tokens, roles), Spring Data JPA, Hibernate Vector & Envers (auditing), Spring Cloud Gateway (WebMVC) & Config Server, springdoc OpenAPI, Actuator.
• Data & processing: PostgreSQL 17 + pgvector + tsvector, Flyway, RabbitMQ, AWS S3 SDK / MinIO, Apache PDFBox / POI / Tika (with language detection), JTokkit, OpenAI chat and embedding models.
• Frontend: React 19, TypeScript, Vite, Ant Design, React Router, TanStack Query, Zustand, Axios, Zod; Vitest, React Testing Library, MSW, ESLint, Prettier, Husky + lint-staged.
• Infra: Docker Compose (pgvector, RabbitMQ, MinIO).

Daily sales, purchasing, stock tracking, kitchen-screen workflows and fast billing.

• I led the whole team, contributed code, and delivered the system to the client, who now runs it.
• Deployed on AWS (S3, EC2) with Docker.

Multi-vendor e-commerce platform.

bKash-style mobile banking: P2P transfers, statements, account details and several user types.

• Fintech client, name confidential.
• I fixed backend bugs and redesigned the whole portal in Thymeleaf.

CMS for React applications, planned as open source.

• I worked on content-management components and left the project mid-development.

Azerion's multi-cloud billing platform, a separate product from Marketplace. I built the whole backend: two services that pull cloud billing data together into one portal.

• Batch service: fetches AWS, GCP and Huawei Cloud billing data and normalizes it.
• Backend service: serves the portal. It shows per-account and all-account billing for multiple cloud accounts in one place, plus cost forecasts.
• Multi-tenant with data isolation and RBAC. Authentication started as Spring Security + JWT and was later moved to the company SSO.
• Fully covered by unit and integration tests.

Pharmacy ERP for pharmacies across Bangladesh: inventory and expiry tracking, POS, sales, expenses and per-user accounting.

• Handles about 1M requests a day, with real-time inventory sync across 200+ branches (now 700+ branches and 3,000+ users).
• Offline mode with online/offline workflows; takes in online orders from the Oushod Sheba app.
• Drug-combination safety alerts and secure handling of patient data; mobile app for running the pharmacy shop.

Online medicine, health and beauty delivery service in Bangladesh, on web (Next.js SSR) and mobile (Flutter), with a React admin portal.

• Includes GPS delivery tracking, route planning and secure payments.
• Backend: Spring Boot, MySQL, MongoDB and Redis caching.
• Part of the same platform family as OS Pharmacy.

Custom-clothing marketplace: customers choose designs and fabrics, and designers upload designs to sell.

• I built it end to end with two other engineers.

German shop-promotion app that shows customers discount offers from nearby shops.

Locker-storage booking: owners list storage, and users book it by area and size.

• I built server-side-rendered Next.js frontends (with Laravel, MySQL and Memcached).

Stock-exchange portfolio tool for viewing company history and projections and comparing companies to support decisions.