Dhaka, Bangladesh · Open to remote opportunities

Ragib Hasan

Engineering Lead & Technical Architect

Specializing in Multi-Tenant SaaS • Microservices • Cloud Infrastructure

Currently
Leading full-stack architecture at Qzency
Project leadership • System architecture • Team mentoring
Core Expertise
• Full-Stack System Architecture
• Microservices & APIs
• Cloud Infrastructure & DevOps
• Database Design & Optimization
• Technical Leadership & Mentoring
• Performance Engineering
Recent Impact & Achievements
Solo-built complete backend infrastructure for ZOYEQ (6 microservices) serving 500+ active stores
Architected multi-tenant SaaS for 100K+ scale with 100% data isolation
Processing 100K+ monthly transactions with complete monitoring stack
Led 6-person team while delivering 60% deployment time reduction
Built ERP system handling 10K+ daily orders for Bangladesh's largest distributor
Resolved a critical database connection exhaustion issue, cutting peak connections 94% and cold starts from 45s to 3s

Experience

6+ years building scalable systems and leading engineering teams

Engineering Lead

atQzency
Jul 2024 - Present

Sole Engineering Lead and backend architect for ZOYEQ, a multi-tenant SaaS integrating e-commerce, POS, inventory, and AI modules.

  • Served as sole Engineering Lead and backend architect, leading a cross-functional team of 6 to deliver ZOYEQ end-to-end, serving 500+ active tenants
  • Resolved a critical database connection exhaustion issue via lazy initialization and LRU eviction, cutting peak connections 94% and cold starts from 45s to 3s
  • Engineered a fault-tolerant, event-driven microservices ecosystem with RabbitMQ, decoupling services to handle high-concurrency workloads without downtime
  • Integrated Google Gemini AI for automated product content, SEO generation, dynamic landing pages, and malicious-code detection on user-submitted inputs
  • Orchestrated a fully automated CI/CD pipeline with GitHub Actions and Kubernetes, cutting deployment time by 60%

Sr. Software Engineer

atDX Group
May 2023 - Jun 2024

Architected ERP systems for DX Group, Bangladesh's largest electronics distributor and national distributor for Xiaomi.

  • Built ERP system processing 10,000+ daily orders
  • Designed multi-organization architecture with data isolation
  • Reduced manual reporting work by 75%

Software Engineer

atMethod Melody
Aug 2021 - May 2023

Built and optimized Learning Management Systems.

  • Delivered LMS platform serving 10,000+ students
  • Reduced server costs by 35% through optimization
  • Led team expansion and mentored junior developers

Web Developer

atClimax IT
Jan 2021 - Jul 2021

Full-stack development and system integration.

  • Delivered multiple client projects on time
  • Implemented secure payment gateway integrations

Jr. Software Engineer

atAlliant Ltd.
May 2020 - Nov 2020

Started career in enterprise software development.

  • Built database management systems
  • Learned enterprise development practices

Engineering Deep Dive

Technical writing on architecture decisions and lessons from production

Featured
December 202518 min read

Architecting for N-Tenants: Database Connection Exhaustion

How we scaled from 300 to N tenants without adding infrastructure. The fix? Replace eager connection initialization with lazy loading, promise caching, and LRU eviction.

Impact Snapshot
Before3,000 connections at boot
After0 connections at boot
Result94% reduction in peak connections
#Node.js
#System Design
#MongoDB
#Multi-Tenancy
#Microservices
Read the Full Deep Dive
May 202612 min read

Event-Driven Microservices: Decoupling Services with RabbitMQ

How backend services publish events through RabbitMQ instead of calling each other directly, with retry queues, dead lettering, and idempotent consumers, built as an event-driven system from day one.

Impact Snapshot
ArchitectureEvent-driven from day one
Scale1M+ events/day
On failureAuto-retry, then dead letter queue
#Node.js
#RabbitMQ
#System Design
#Microservices
#Event-Driven Architecture
Read the Full Deep Dive
August 202610 min read

The Transactional Outbox Pattern: Making Event Publishing Atomic

How to guarantee a database write and the event it triggers either both happen or neither does, closing the one gap the RabbitMQ post left open, with a polling relay, a change-stream alternative, and where else the pattern applies.

Impact Snapshot
ClosesSilent event-loss gap
MechanismSame-transaction outbox row
DeliveryStill at-least-once, by design
#Node.js
#MongoDB
#RabbitMQ
#System Design
#Distributed Systems
Read the Full Deep Dive

Remote Work Ready

Equipped with the infrastructure, skills, and mindset to thrive in remote-first environments. Proven ability to deliver enterprise-grade systems independently.

Global Collaboration Ready

Experienced in coordinating with distributed teams and stakeholders

Flexible Schedule

Available for overlapping hours with US/EU/APAC time zones

Clear Communication

Strong written and verbal skills for effective async collaboration

Reliable Setup

Dedicated home office with fiber internet (100Mbps+) and backup power

Remote Tools Proficient

Proficient with Slack, Zoom, Jira, GitHub, Notion, Linear

Self-Driven

Proven track record of delivering complex projects independently

Open to Remote Opportunities Worldwide

Available for full-time positions • Can start within 2-4 weeks • Open to relocation for the right opportunity

Technical Expertise

Comprehensive full-stack capabilities spanning architecture design, cloud infrastructure, monitoring, and team leadership across the entire software development lifecycle.

Backend & Architecture

Node.js
Express.js
NestJS
Microservices
System Design
API Design
Database Architecture
Event-Driven Architecture
Scalable Systems

Databases & Storage

MongoDB
PostgreSQL
Redis
Database Optimization
Data Modeling
Query Optimization
Caching Strategies
Replication

Cloud & DevOps

AWS
Docker
Kubernetes
NGINX
CI/CD Pipelines
Distributed Systems
Generative AI/LLM Integration
Infrastructure as Code
Container Orchestration
Load Balancing
Auto Scaling

Monitoring & Observability

Grafana
Prometheus
ELK Stack
Application Performance Monitoring
Log Aggregation
Metrics Collection
Alerting Systems
Distributed Tracing

Frontend & Tools

React.js
Next.js
TypeScript
JavaScript
Tailwind CSS
State Management
Server-Side Rendering
Performance Optimization

Message Queues & Integration

RabbitMQ
Socket.io
Event Streaming
Message Patterns
API Integration
Third-party Services
Webhook Management
Data Synchronization
Real-time Communication

Leadership & Product Strategy

End-to-End Product Lifecycle
Stakeholder Management
Startup Operations
Release Planning
Agile/Scrum Leadership
Technical Mentorship

Passionate about building robust, scalable systems and leading engineering teams to deliver exceptional results through technical excellence and collaborative leadership.

Technical Leadership

End-to-end project ownership from architecture design to deployment, leading cross-functional teams and delivering scalable solutions.

ZOYEQ - Multi-Tenant E-Commerce SaaS Platform

Engineering Lead & Architect (Solo Backend & Infrastructure)

Enterprise-grade multi-tenant SaaS integrating e-commerce, POS, and inventory management, with AI-powered content modules built in. Single-handedly architected and built complete backend infrastructure (6 microservices) from concept to production, serving 500+ active tenants on separate databases per tenant. Integrated Google Gemini AI for content generation and security scanning, 4 payment gateways (SSLCommerz, bKash, Stripe, PayPal), and comprehensive monitoring stack (Prometheus, Grafana, Loki).

94% fewer connections45s → 3s cold startLIVE REQUESTStenant_4a1ftenant_9c22REGISTERED TENANTS0 open connections500+ registered tenants, most idle, none holding a connectionTenantConnectionManager1 check active pool2 reuse, or open +cache the promise3 evict after 30m idletenant_4a1f · dbtenant_9c22 · dbMongoDB Atlas: one isolateddatabase per tenantLEGENDactive connectionidle, no connection
ZOYEQ opens a database connection only for tenants that are actually active. Idle tenants (the majority at any given moment) hold zero open connections, which is what let the platform scale past 300 tenants without adding infrastructure.

Key Achievements

Solo-built 6 production microservices (Gateway, Core, Store-Core, Store-Product, Store-Order, Notification)
Designed for 100,000+ tenant scalability with connection pooling and database sharding preparation
Achieved 100% data isolation with separate MongoDB database per tenant
Built complete CI/CD pipeline with GitHub Actions and Kubernetes, reducing deployment time by 60%
Kubernetes deployment with HPA and comprehensive monitoring (Prometheus, Grafana, Loki)
Redis caching layer reducing database load by 80% (800ms → <150ms response time)
Resolved a critical connection exhaustion issue via lazy initialization and LRU eviction, cutting peak connections 94%, cold starts from 45s to 3s
Integrated Google Gemini AI for product content, SEO generation, dynamic landing pages, and malicious-code detection on user-submitted inputs (99% success rate)
4 payment gateway integration (SSLCommerz, bKash, Stripe, PayPal) with tenant-specific routing
Multi-warehouse inventory system with real-time synchronization
Event-driven architecture with RabbitMQ capable of handling 1M+ daily events
500+ active stores in production with 99.9% uptime
Capable of processing millions of monthly transactions with zero payment failures
Led 6-person cross-functional team with full project ownership
Domain routing supporting subdomains and custom domains with auto tenant detection

Technology Stack

Node.js
Express.js
Next.js
MongoDB
Redis
Docker
Kubernetes
AWS
RabbitMQ
Socket.io
Prometheus
Grafana
Loki
Gemini AI
TypeScript

EBS - Enterprise Resource Planning

Technical Lead & System Architect

Full-scale ERP solution architected for DX Group, Bangladesh's largest electronics distributor, handling complex supply chain and inventory management.

Key Achievements

Architected complete system from ground up
500+ concurrent users supported
20+ integrated modules
40% operational efficiency gain
Real-time inventory tracking across 50+ locations

Technology Stack

Node.js
Express.js
Next.js
MongoDB
Docker
AWS
Redis
RabbitMQ
TypeScript

Ticketing & Event Management Platform

Full-Stack Developer & Technical Lead

Scalable ticketing platform with real-time seat selection, payment processing, and comprehensive event management capabilities.

Key Achievements

Led complete platform development
10K+ concurrent users during peak events
Real-time seat selection with conflict resolution
Integrated payment processing with 99.9% uptime
Event analytics dashboard with advanced reporting

Technology Stack

Node.js
React.js
MongoDB
Socket.io
Stripe API
AWS
Docker
Redis

Education & Publications

Academic background and research contribution in modern video game development

Education

Bachelor of Science, Computer Science & Engineering

University of Asia Pacific • Dhaka • Graduated 2020

Publications

Character and Mesh Optimization of Modern 3D Video Games

Published in Lecture Notes in Networks and Systems • Springer, Singapore

January 2020 • Conference Paper

Introduced methodology to optimize 3D mesh for wide hardware compatibility, demonstrating significant performance improvements through poly count reduction.

Contact

Let's discuss opportunities, collaborations, or technical challenges