I am Abid.

Senior Backend Engineer / Tech Lead

Md. Abid Hasan

Senior Backend Engineer & Tech Lead with 8+ years of experience architecting high-throughput, distributed systems for telecom and enterprise platforms. Expert in Java, Kotlin, Spring Boot, and reactive microservices, with a deep focus on scalability, performance optimization, and production reliability.

Led large-scale AI-assisted legacy modernization and designed AI-driven RAG-based platforms. Optimized systems to handle up to 800 TPS/node with 99.9% availability, while improving operational efficiency and customer satisfaction.

Open to remote & relocation · Available for select freelance engagements
Backend
AI Architecture
Distributed Systems
Java & Spring
Upwork

Technical Skills

Technical expertise and tools I use to build scalable, high-performance solutions.

Backend & Core

Java
Kotlin
Spring Boot
Spring WebFlux
Hibernate/JPA
REST APIs
SOAP
GraphQL

Architecture & Messaging

Microservices
Distributed Systems
Event-Driven Architecture
Apache Kafka
RabbitMQ

Databases & Caching

MySQL
PostgreSQL
MongoDB
MariaDB
Redis
Redis Sentinel

AI & AI-Assisted Engineering

RAG (Retrieval-Augmented Generation)
Vector Search
Prompt Engineering
Agentic Workflows
LangChain
Cursor & Windsurf
Antigravity

Observability & Monitoring

Grafana
Prometheus
SNMP
Structured Logging

Performance & Debugging

JProfiler & VisualVM
Wireshark
Thread/Heap Dump Analysis

DevOps & Cloud

Docker
AWS
GitLab CI/CD
Jenkins

Testing & API Tools

JUnit & Mockito
Testcontainers
Postman & Swagger

Frontend

React
Next.js
Featured Work

Selected Projects

A glimpse into some of the complex systems I've built, from high-throughput gateways to modern architectures.

View All Projects

High-Performance Telecommunications Service Delivery Platform

Engineered a scalable microservices platform processing 500+ messages/second, reducing latency by 75% through RocksDB optimization and JVM tuning.

Java
Spring Boot
Maven
+9 more

Shortened URL Resolver System

High-performance URL resolution service with SSL interception, intelligent caching, and comprehensive reporting capabilities for resolving shortened URLs in real-time

Kotlin
Spring Boot 3.2
Spring WebFlux
+12 more

Digital Office SDP Middleware Platform

Enterprise middleware platform for protocol conversion and request routing between SDP systems and backend services, handling authentication, bundle subscriptions, balance queries, and credit transactions with high availability and observability.

Java
Kotlin
Spring Boot
+10 more

Oredoo Customer Care System

Enterprise-grade customer care and analytics platform for telecom operations, enabling real-time CDR processing, advanced search capabilities, and comprehensive reporting

Java
Spring Framework
Spring Boot
+12 more

Insights

Kafka Streams Part 3: Making It Production-Ready
August 25, 2026•13 min read•Backend

Kafka Streams Part 3: Making It Production-Ready

Take Kafka Streams to production — custom Serdes, event time, exactly-once processing, error handling with dead-letter queues, scaling, testing, and the mistakes everyone makes.

Read Article
Kafka Streams with Spring Boot: Real-Time Pipelines the Spring Way
August 25, 2026•11 min read•Backend

Kafka Streams with Spring Boot: Real-Time Pipelines the Spring Way

Build a production-shaped streaming app with Spring Boot and Spring Kafka — REST input, JSON events, running aggregates, and windowed fraud alerts, with Spring managing all the plumbing.

Read Article
Kafka Streams Part 1: Stream Processing Made Simple
August 25, 2026•12 min read•Backend

Kafka Streams Part 1: Stream Processing Made Simple

Learn what Kafka Streams is, why it exists, and build your first real-time word counting app — explained in plain words with working code you can run today.

Read Article

Testimonials

Trusted By

Working with Abid across our Sri Lanka and Bangladesh teams, he proved to be an exceptional senior developer — high-quality work, delivered independently and always on time. He explains complex technical concepts in clear, accessible terms and acted as an informal mentor who elevated the whole team.
AL
Amith Lokugamage
Senior Business Analyst · GovTech Singapore
LinkedIn
An exceptionally talented Senior Backend Engineer and Tech Lead. His architectural thinking and clean coding turn complex requirements into scalable, reliable solutions — and he leads by example: calm under pressure, solution-oriented, always ready to jump on a call no matter the time zone.
LW
Lahiruka Wijesinghe
Adelaide University · Adelaide University
LinkedIn
Abid understands complex requirements quickly and consistently suggests alternative approaches that improve efficiency and quality. Having him on the team gave me full confidence in our technical delivery — a responsible, dependable problem solver.
KR
Kaniyout Ranjan J
Operations Manager · hSenid Mobile Solutions
LinkedIn
My top three adjectives for Abid: extremely passionate, loving, and fast learner. We worked together for over a year, and he has a remarkable ability to take on new challenges with a genuine drive for continuous improvement.
SI
Shakibul Islam
Software Architect · Neumann Kaffee Gruppe
LinkedIn
Abid works well under pressure and continuously meets expectations, with strong object-oriented programming and design-pattern fundamentals. I recommend him as a very good resource for any project.
MM
Md Mobarak Hosen
Software Architect · TechnoNext
LinkedIn
Working with Abid across our Sri Lanka and Bangladesh teams, he proved to be an exceptional senior developer — high-quality work, delivered independently and always on time. He explains complex technical concepts in clear, accessible terms and acted as an informal mentor who elevated the whole team.
AL
Amith Lokugamage
Senior Business Analyst · GovTech Singapore
LinkedIn
An exceptionally talented Senior Backend Engineer and Tech Lead. His architectural thinking and clean coding turn complex requirements into scalable, reliable solutions — and he leads by example: calm under pressure, solution-oriented, always ready to jump on a call no matter the time zone.
LW
Lahiruka Wijesinghe
Adelaide University · Adelaide University
LinkedIn
Abid understands complex requirements quickly and consistently suggests alternative approaches that improve efficiency and quality. Having him on the team gave me full confidence in our technical delivery — a responsible, dependable problem solver.
KR
Kaniyout Ranjan J
Operations Manager · hSenid Mobile Solutions
LinkedIn
My top three adjectives for Abid: extremely passionate, loving, and fast learner. We worked together for over a year, and he has a remarkable ability to take on new challenges with a genuine drive for continuous improvement.
SI
Shakibul Islam
Software Architect · Neumann Kaffee Gruppe
LinkedIn
Abid works well under pressure and continuously meets expectations, with strong object-oriented programming and design-pattern fundamentals. I recommend him as a very good resource for any project.
MM
Md Mobarak Hosen
Software Architect · TechnoNext
LinkedIn
One of the brightest developers I have worked with — well-organized, high-quality, maintainable code, an eye for detail and quick execution. A great asset and a true team player.
MA
Mahmud Al-Noor Tareq
Software Development Engineer II · Amazon
LinkedIn
A terrific developer I would rely on for any of my projects — a smart thinker, quick learner and very efficient at solving critical problems, and a cooperative team player who makes life easier for his teammates.
SB
Sabid Bin Habib Pias, PhD
Postdoctoral Researcher · AI & Society Research Center
LinkedIn
Abid became an asset to my team very fast — the speed and accuracy of his development is often astonishing. Any manager would be happy to have him on their team.
MT
Md. Tariqul Islam
Team Leader · Product Manager
LinkedIn
A talented developer with excellent software development skills. Working with him for around a year, I found him enthusiastic and hard-working — excellent at designing and developing Android apps and backend services.
MH
Md Hasanuzzaman
Mobile Engineer · Android, iOS, Java, Kotlin, Flutter
LinkedIn
Very talented, humble and genuinely funny. Whenever we hit a problem, he would listen carefully and come back with a solution in a very short time — passionate, a technology enthusiast and a quick learner.
AR
Abdur Razzak
Software Engineer · Java, Kotlin, Spring Boot
LinkedIn
One of the brightest developers I have worked with — well-organized, high-quality, maintainable code, an eye for detail and quick execution. A great asset and a true team player.
MA
Mahmud Al-Noor Tareq
Software Development Engineer II · Amazon
LinkedIn
A terrific developer I would rely on for any of my projects — a smart thinker, quick learner and very efficient at solving critical problems, and a cooperative team player who makes life easier for his teammates.
SB
Sabid Bin Habib Pias, PhD
Postdoctoral Researcher · AI & Society Research Center
LinkedIn
Abid became an asset to my team very fast — the speed and accuracy of his development is often astonishing. Any manager would be happy to have him on their team.
MT
Md. Tariqul Islam
Team Leader · Product Manager
LinkedIn
A talented developer with excellent software development skills. Working with him for around a year, I found him enthusiastic and hard-working — excellent at designing and developing Android apps and backend services.
MH
Md Hasanuzzaman
Mobile Engineer · Android, iOS, Java, Kotlin, Flutter
LinkedIn
Very talented, humble and genuinely funny. Whenever we hit a problem, he would listen carefully and come back with a solution in a very short time — passionate, a technology enthusiast and a quick learner.
AR
Abdur Razzak
Software Engineer · Java, Kotlin, Spring Boot
LinkedIn

Work Experience

A journey through my professional growth, from junior developer to tech lead, specializing in backend development and AI-assisted engineering practices.

  1. Tech Lead

    hSenid Mobile Solutions PVT Limited
    Current
    April 2024 - PresentDhaka, Bangladesh
    Hybrid
    • AI-Driven Customer Support & Search: Built a RAG-based contextual search feature for development guides and reporting using vector search and prompt engineering; improved customer satisfaction by 20% and slashed resolution time by 1/6th.
    • Legacy Modernization (Java 6 → 21): Orchestrated full-scale system migration using AI-assisted development (Cursor & Antigravity), completing the migration in 36h vs. 80h estimated.
    • Led two telecom-grade projects from kickoff to production, delivering 95% on time without compromising stability.
    • Optimized delivery by matching work to engineers' strengths and clarifying ownership, cutting sprint rollover from 60% → 30%.
    • Migrated legacy reporting from custom solutions to Grafana dashboards, reducing new development time and cost by 25%.
    • Coached junior engineers through structured code reviews, raising independent task completion from 50% → 70% per sprint.

  2. Associate Tech Lead

    hSenid Mobile Solutions PVT Limited
    October 2022 - March 2024Colombo, Sri Lanka
    Remote
    • Enterprise URL Resolver & Firewall: Designed and implemented a high-throughput URL resolution firewall system with SSL bumping, achieving 800 TPS/node with sub-5ms response latency using Redis caching and Sentinel.
    • SMS Delivery Redesign: Reworked the SMS delivery report pipeline (600–800 TPS), lifting reliability from 65% → 99.9% by splitting a brittle single-table design into an async dual-table flow.
    • Built a reactive middleware protocol converter using Spring WebFlux to migrate legacy integrations while preserving API contracts, increasing billing throughput by 40%.
    • Implemented event-driven metrics and monitoring (SNMP, TPS tracking, transaction logs) using async logging and non-blocking processing for full observability.

  3. Senior Software Engineer

    hSenid Mobile Solutions PVT Limited
    September 2021 - September 2022Colombo, Sri Lanka
    Remote
    • 5G Authentication Systems: Improved query performance by 4x in 5G authentication systems through advanced indexing and caching strategies.
    • Production Reliability: Investigated and resolved production incidents through comprehensive analysis of thread/memory dumps and network traces; optimized performance using VisualVM and JProfiler.
    • Built RESTful services supporting 10K+ concurrent users across MySQL, MongoDB, and MariaDB environments.
    • Maintained and enhanced legacy Java 6 systems through active feature development and migration planning, ensuring production stability.

  4. Software Engineer

    hSenid Mobile Solutions PVT Limited
    September 2019 - September 2021Dhaka, Bangladesh
    Onsite
    • Appigo Pay: Integrated HSBC and HNB bank support into a custom payment gateway, facilitating secure transaction processing for major financial institutions.
    • M1-SDP: Added multi-language and Unicode support to a legacy SMS delivery platform.
    • Developed microservices architecture using Spring Boot and Docker; optimized SQL queries to double enterprise authentication server performance.

  5. Jr. Software Engineer (Android)

    Field Buzz (Field Information Solutions GmbH)
    June 2018 - September 2019Dhaka, Bangladesh
    Onsite
    • Developed dynamic Android form builder library using Java & Kotlin.
    • Improved app stability by 25% through performance tuning and code refactoring.

Academic Background

Education and qualifications that provided the foundation for my engineering career.

Bachelor of Science in Computer Science & Engineering

North South University

Graduated 2018
Dhaka, Bangladesh