M
Available for senior backend rolesAdelaide, Australia

Senior software engineer building scalable fintech & payment systems.

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Majharul Islam avatar
Signal clear·Shipping since 2019
5+
Years engineering
800+
Brands on Vezmo
200M+
Catalogue scale
4
IEEE publications
About

Money moves through code I write — so I write it like it's load-bearing.

I'm a senior backend engineer who builds the load-bearing parts of fintech and SaaS products. Five years of shipping Node.js and TypeScript services into regulated environments — Central Bank-licensed payment operators, Buy Now Pay Later platforms with AI-driven credit decisioning, and finance SaaS serving hundreds of brands worldwide. I lead the work end to end: architecture, APIs, security, observability, and the unglamorous reliability details that quietly decide whether a system survives its first real scale event.

  • 01

    Architect for change

    Bounded contexts, versioned contracts, and reversible decisions. Systems should be safe to evolve, not just safe to ship.

  • 01

    Boring where it matters

    Postgres, queues, idempotent APIs, observable releases. Novelty belongs in product, not in the load-bearing parts of the stack.

  • 01

    Production is the spec

    Contracts, audit trails, and rollback paths are designed in. If it can't be observed and rolled back, it isn't done.

Experience

Five years shipping production systems — from monoliths to microservices.

  1. Dec 2023 — Present
    Remote · Malaysia

    Senior Software Engineer

    Moby Money Sdn Bhd

    Build, maintain, and scale a Buy Now Pay Later platform serving Malaysian consumers and merchants — owning core payment, credit, and merchant-integration surfaces.

    • Built KYC onboarding and identity verification pipelines integrating third-party providers, document checks, and risk signals.
    • Built an AI-driven auto-limit assignment engine that infers a starting credit limit from user profile signals and credit history at onboarding — removing manual underwriting from the new-user path.
    • Designed an AI-driven credit assignment engine for Increase-Limit applications — automating decisioning that previously required manual review.
    • Re-architected scheduled jobs (repayment runs, late-fee accruals, statement generation) to be horizontally scalable and idempotent under retries.
    • Upgraded and scaled the Pay Now and Installment payment flows — improving throughput, reducing failed transactions, and tightening reconciliation.
    • Owned merchant integration: onboarding APIs, checkout SDK contracts, settlement workflows, and partner-facing webhooks.
    Node.jsPHP/LaravelMySQLDockerAWSRedis
  2. May 2023 — Nov 2023
    Remote · Bangladesh

    Senior Software Engineer

    HelloPay Ltd.

    Architected the MVP for a Payment Service Operator licence — a regulated fintech product for the Central Bank of Bangladesh.

    • Built compliant KYC, ledger, and transaction services in NestJS with PostgreSQL and clear domain boundaries.
    • Implemented secure authentication, RBAC, and immutable audit trails to satisfy regulator expectations.
    • Owned containerised deployment on DigitalOcean with repeatable build/release/rollback workflows.
    • Led a cross-functional Agile team through architecture, planning, and production rollout.
    NestJSTypeScriptPostgreSQLReactDockerDigitalOcean
  3. Jul 2021 — Apr 2023
    Remote · E-commerce

    Software Engineer · Lead Developer

    Accept Global Ltd.

    Lead developer for wholesalecart.com — winner of the South Asian Business Excellence Award 2022 for Best B2B E-Commerce Website, and at the time the country's leading dropshipping platform.

    • Replatformed the business off a slow Shopify storefront onto a scalable Laravel + React stack, lifting page speed, throughput, and customisation headroom.
    • Ran a phased catalogue, customer, and order migration with dual-write cutover — zero merchant downtime through the transition.
    • Designed versioned REST APIs with idempotency, pagination, and rate limiting; hardened endpoints with input validation and structured error handling.
    • Set up CI/CD with staging, automated smoke tests, and zero-downtime production deploys.
    • Partnered with marketing and data teams on centralised logging, analytics, and reporting pipelines.
    LaravelPHPReactMySQLRedisNode.js
  4. Apr 2020 — Jun 2021
    Remote · Italy

    Software Engineer

    Asyncus

    End-to-end backend delivery for client projects — from requirements through deployment.

    • Built and consumed REST APIs across React frontends with full CI/CD coverage.
    • Owned architecture, deployment configuration, and automated release pipelines.
    LaravelPHPMySQLReactJavaScript
  5. Jun 2019 — Mar 2020
    Remote · International

    Freelance Software Developer

    Fiverr Inc.

    Custom backend solutions for international clients across e-commerce and business management — Node.js, Express, MongoDB, and PHP stacks.

    • Managed pre-sale analysis, scoping, and client communication independently.
    • Shipped production features under tight client SLAs and review cycles.
    Node.jsExpressMongoDBPHP
Selected Work

Six flagship systems — each shipped, scaled, and audited in production.

Consultant & Technical Lead

Vezmo

Unified business & finance platform for 800+ brands worldwide.

SMBs juggle invoicing, payments, contracts, billing, and bookkeeping across disconnected tools. Vezmo unifies them into a single API-first platform — built to launch with regulator-grade security and partner-grade integrations from day one.

Architecture
  • Microservices split by domain — Invoicing, Payments, Contracts, Bookkeeping, Billing, and Identity.
  • REST plus event bus — synchronous APIs for partners, async events for invoice lifecycle, recurring billing, and notifications.
  • Public API surface with OAuth2 / JWT, webhook delivery, and a rate-limited integration layer.
  • Encryption at rest and in transit, audit trails, RBAC, and regulator-friendly data handling.
  • CI/CD pipelines, containerised deploys, and structured logging, metrics, and tracing across services.
800+
brands onboarded
6
core domains
99.9%
release reliability
Node.jsTypeScriptPostgreSQLEvent BusAWSDocker
Senior Software Engineer

Moby BNPL Platform

Buy Now Pay Later platform for Malaysian consumers and merchants.

Run a regulated BNPL product end-to-end — onboard consumers via KYC, assign credit limits intelligently, process Pay Now and installment payments at scale, and settle reliably with merchants under tight reconciliation guarantees.

Architecture
  • KYC onboarding pipeline integrating third-party identity providers, document verification, and risk signals.
  • AI-driven auto-limit assignment at onboarding — infers a starting credit limit from profile signals and credit history.
  • AI-driven decisioning for Increase-Limit applications — automating reviews previously done manually.
  • Horizontally scalable scheduled jobs for repayment runs, late-fee accruals, and statement generation with idempotent retries.
  • Merchant integration suite — onboarding APIs, checkout SDK contracts, settlement workflows, and partner webhooks.
AI
credit decisioning
Scaled
scheduled jobs
Live
merchant integrations
Node.jsPHP/LaravelMySQLRedisAWSDocker
Senior Software Engineer

HelloPay PSO MVP

Central Bank of Bangladesh-licensed payment service operator MVP.

Stand up a regulated payment service operator from zero — KYC, ledger, transaction APIs, and admin tooling — at a quality bar acceptable to the central bank, with full audit trails and zero-data-loss guarantees.

Architecture
  • NestJS microservices with explicit bounded contexts — KYC, Ledger, Transactions, and Admin.
  • PostgreSQL with double-entry ledger semantics and immutable audit logs.
  • Hardened auth (JWT + role policies), per-endpoint rate limiting, and full request/response audit trail.
  • Containerised deploys on DigitalOcean with repeatable build, release, and rollback tooling.
  • Cross-functional Agile delivery — architecture, planning, and rollout to regulator sign-off.
PSO
licence approved
100%
regulator audit pass
4
domain services
NestJSTypeScriptPostgreSQLReactDockerDigitalOcean
Lead Developer

Wholesalecart

Award-winning dropshipping platform — replatformed off Shopify onto Laravel + React.

The business had outgrown Shopify — page speed, customisation, and per-transaction costs were all blockers. The mandate was to rebuild on owned infrastructure without losing a single live merchant order during cutover.

Architecture
  • Replatformed off Shopify onto a custom Laravel + React stack — owning the storefront, admin, and merchant tooling end-to-end.
  • Phased catalogue, customer, and order migration with dual-write windows keeping legacy and new systems in sync until cutover.
  • Versioned REST APIs with idempotency, pagination, and rate limiting; React SPA consuming the new contracts.
  • CI/CD with staged deploys, automated smoke tests, and zero-downtime release windows on managed cloud infrastructure.
  • Centralised logging and analytics pipelines feeding the marketing and data teams.
2022
SABE Award winner
Shopify→Custom
platform migration
0min
merchant downtime
LaravelPHPReactMySQLRedisNode.js
Backend Engineer

Onesalemart

Global dropshipping platform with a 200M+ SKU catalogue.

Index, search, and price 200M+ SKUs sourced from third-party suppliers — with reliable order routing, payment processing, and merchant reporting at scale, despite unreliable upstream APIs.

Architecture
  • Bulk ingestion pipeline with batched writes and queue-driven enrichment workers.
  • Search and pricing layer over MongoDB tuned for the long tail of the 200M+ catalogue.
  • Payment gateway and supplier API integrations sitting behind retry-aware adapters with circuit breakers.
  • Order routing engine matching merchant orders to suppliers based on inventory, region, and SLA.
  • Automated reporting jobs producing daily merchant analytics and reconciliation summaries.
200M+
SKUs indexed
Multi
gateway support
Daily
automated reports
Node.jsExpressMongoDBQueue WorkersREST API
Architect & Engineer

School Management SaaS

Multi-tenant, role-based SaaS for schools.

Schools need a single platform serving Admin, Student, Teacher, Director, and Accounts roles — each with sharply different permissions, dashboards, and workflows — without leaking data across tenants.

Architecture
  • Multi-role REST APIs with granular RBAC enforced at the service layer.
  • Tenant-aware data model with logical isolation and per-tenant audit logs.
  • React dashboards per role, sharing a versioned component library and design tokens.
  • Background jobs for attendance, billing runs, and report generation with idempotent retries.
  • CI/CD with environment promotion, smoke tests, and zero-downtime production deploys.
5
distinct role dashboards
Multi-tenant
from day one
Live
production deployment
Node.jsExpressREST APIRBACReactMongoDB
System Design

Patterns I reach for — proven in regulated fintech and high-traffic e-commerce.

01

Event-Driven Payments

Authorisation API decouples from ledger and reconciliation via durable queues. Idempotency keys + DLQs guarantee at-least-once processing without double-charging.

API Gateway
Auth Service
Queue
Ledger
Reconciler
DLQ
02

Microservices Boundaries

Domains split along business capability — Identity, Invoicing, Payments, Bookkeeping. Each owns its data; cross-domain workflows ride the event bus.

Identity
Invoicing
Payments
Bookkeeping
Event Bus
03

Scalable Read Path

Edge caching + Redis hot keys + read replicas absorb burst traffic. Cache invalidation rides the same event bus that drives ledger writes.

CDN
API
Redis
Read Replica
Primary DB
04

Zero-Downtime Releases

Blue/green Docker deploys behind a load balancer, with database migrations run as expand-then-contract. Health checks gate traffic shift.

LB
Blue
Green
Migrations
Health Checks
Toolkit

Tools I trust in production.

Backend
  • Node.js
  • NestJS
  • Express.js
  • TypeScript
  • REST APIs
  • GraphQL
  • Microservices
  • Event-driven
Frontend
  • React
  • Redux
  • TypeScript
  • Next.js
  • HTML5
  • CSS3
  • Tailwind
Cloud & DevOps
  • AWS
  • DigitalOcean
  • Docker
  • GitHub Actions
  • GitLab CI
  • Linux
  • Zero-downtime deploys
Databases
  • PostgreSQL
  • MySQL
  • MongoDB
  • Redis
Security
  • OAuth2 / JWT
  • OWASP Top 10
  • Rate limiting
  • Secrets management
  • RBAC
  • Audit logging
Practices
  • Agile / Scrum
  • Domain-driven design
  • Clean architecture
  • Code review
  • Performance tuning
  • Observability
Education & Research

Master of Artificial Intelligence & Machine Learning

Adelaide University · Adelaide, Australia
Incoming
Aug 2026 — Expected

BSc in Computer Science & Engineering

North South University · Dhaka, Bangladesh
Apr 2016 — Dec 2020

Research

4 IEEE-indexed publications · 110+ citations. Applied ML research in predictive modelling and ensemble methods (LightGBM, XGBoost, Random Forest, SVM, K-Means).

  • IEEE CCWC · Las Vegas, 2023
  • IEEE · Singapore, 2020
  • IEEE · Coimbatore, 2020
Contact

Let's build something that scales.

I'm available for senior backend, platform, and staff roles — full-time or consulting. Best way to reach me is email.

majharul.nayem042@gmail.com
LinkedIn
GitHub

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