.NET 8 · SOFTWARE ENGINEER · 3 YOE

I build dependable software for real business workflows—grounded in production discipline.

Md. Abu Rayhan

Software Engineer · 3 YoE

Over the last 3 years, I developed my engineering foundation under senior mentorship in an established team, and applied those principles to build end-to-end manufacturing, FinTech, and automated data systems.

Explore production systems Download Resume Live BMS demo

3 years hands-on production code across 3 systems Team collaboration & independent system delivery

Md. Abu Rayhan Available

Software Engineer · 3 Years Experience

CAREER EVOLUTION & FOUNDATION

From senior engineer mentorship to independent system delivery

My technical foundation is grounded in two distinct phases: absorbing production discipline under senior engineers in a team, and subsequently taking sole responsibility for an end-to-end enterprise build.

PHASE 01 · DEVSFAIR (2+ YEARS)Dec 2023 — Mar 2026

Core foundation built under senior guidance

My core engineering foundation was developed working inside an established engineering team under direct senior mentorship. Through rigorous code reviews, feature implementation, and production troubleshooting, I learned how enterprise code must be built for maintainability and security.

Enterprise security: Multi-tenant isolation and role-based data boundaries in FinTech.

Database hygiene: CQS data access with Dapper and high-throughput SQL Server persistence.

Resilience & testing: Automated ETL retry policies with exponential backoff and xUnit test suites.

Team Role · Mentored by Senior Engineers

PHASE 02 · VAATCOBMSApr 2026 — Present

Independent system architecture & delivery

Armed with the principles learned from senior engineers, I stepped up to independently design, architect, and deploy VaatcoBMS from the ground up—translating messy real-world factory operations into an immutable, double-entry accounting and ERP platform.

Physical vs financial truth: Anchoring inventory carrying values against factory scale variances.

Audit integrity: Reversal-only immutable journals that eliminate silent back-dated edits.

Concurrency guards: PostgreSQL row-version triggers preventing simultaneous overwrite loss.

Sole Software EngineerProduction Live

PRODUCTION SYSTEMS / 3 YEARS OF WORK

Three core production systems built for real operations

Equal focus on the three major software systems I built and contributed to—spanning enterprise FinTech, high-throughput automated ETL, and manufacturing ERP.

SYSTEM 01 · FLAGSHIP BUILDApr 2026 — Present

Sole Software Engineer

VaatcoBMS — Manufacturing ERP & Double-Entry Accounting

A complete pharmaceutical and aquaculture manufacturing platform connecting physical factory floor operations (scale tolerance, bulk mixing, QA returns) to an immutable financial general ledger.

Headache 01 · Dispensing Scale VarianceFactory Floor

Bulk material weights vary on factory dispensing scales due to tare/moisture. Naive systems change quantities without updating carrying values, causing GL inventory balances to decouple from warehouse reality.

How It Was SolvedAnchored Value

Anchors carrying value while letting unit rate float (UnitCost = CarryingValue / CurrentStock). Every movement automatically syncs GL inventory control accounts in one transaction with zero tolerance on counted packaging.

Headache 02 · Disconnected Sales Delivery & Phantom InventoryUnified 4-Stage Lifecycle

Field booking without credit checks, warehouse dispatch creating phantom stock, untracked carton costs & transport logistics (Truck, Courier, Hand Delivery), and diverging dealer dues—solved by consolidating the entire lifecycle into one tamper-proof platform:

1. Field BookingStock hints & credit checks (read-only post-booking)

2. Carton PackingPM carton allocation & staging readiness

3. Chalan DispatchFEFO lock, transport logistics (Truck/Courier/Hand), chalan

4. Invoice & GLDouble-entry GL, packaging expense, canonical due sync

C# · .NET 8 · PostgreSQL · Double-Entry Ledger · QuestPDF · Docker · Azure

KEY INVARIANTS ENFORCED

Reversal-only immutable journals (IsPostedToGl == true)
Single canonical customer due formula across all views & PDFs
PostgreSQL row-version triggers catching simultaneous updates

Read full case study Open live application

SYSTEM 02 · ENTERPRISE FINTECHDevsfair · Team Build

Backend & Blazor Contributor

Financial Assistant Software — Multi-Tenant Receivables & Credit

A financial receivables, payables, and credit management platform serving corporate entities, lending affiliations, and borrower relationships.

Operational Headache Solved:

Multiple competing lending institutions and multi-company borrowers sharing a single database platform without risking data leakage, unverified loan documents, or fragile repayment schedules.

How It Was Built:

Built secure multi-tenant data isolation and role-based permissions, ASP.NET Core 8 Web API endpoints, Dapper CQS data access, Azure Blob secure document vaults, and responsive Blazor UI components.

C# · .NET 8 · ASP.NET Core Web API · Dapper · MS SQL Server · Azure Blob · Blazor · Clean Architecture

TEAM CONTRIBUTION & DELIVERABLES

Strict multi-tenant query isolation preventing cross-company data exposure
Secure Azure Blob storage pipelines for confidential loan documentation
Reusable Blazor UI components with client & server-side validation
Domain-driven validation and automated unit test coverage

Developed & maintained inside Devsfair agile product team

SYSTEM 03 · DATA PIPELINES & ETLDevsfair · Team Build

ETL & Testing Contributor

Sports API — Automated Data Integration & Sync Engine

A high-throughput recurring synchronization engine that ingests large, unstructured third-party data feeds into normalized SQL Server schemas across multiple sports entity types.

Operational Headache Solved:

Manual data updates were slow and error-prone. External API feeds frequently rate-limited, dropped connections midway, or sent malformed payloads that silently corrupted reporting tables.

How It Was Built:

Implemented resilient API clients with exponential backoff and circuit breaker retry policies. Built high-speed Dapper / ADO.NET bulk-insert pipelines with schema validation and xUnit regression safety nets.

C# · .NET 8 · Dapper · ADO.NET · MS SQL Server · xUnit · CQS · Background Workers

RELIABILITY & DATA INVARIANTS

Exponential backoff retry policies handling third-party rate limits seamlessly
High-throughput Dapper bulk mapping maintaining transaction atomicity
Comprehensive automated xUnit regression suites mocking edge-case payloads
Zero-downtime scheduled ETL execution with structured error logging

Automated data pipeline running in production

TECHNICAL STACK

Tools & technologies

Grouped by the practical work they support in production across all three systems.

Languages & Frameworks

C# · .NET 8 · ASP.NET Core Web API · ASP.NET Core MVC · Blazor · SQL · JavaScript

Data & Persistence

PostgreSQL (Npgsql) · MS SQL Server · Entity Framework Core · Dapper · ADO.NET · MySQL

Architecture & Rules

Double-entry ledger modeling · Domain invariants · Clean Architecture · CQS / CQRS · Unit of Work

Testing & Reliability

xUnit · Moq · FluentAssertions · Concurrency tokens · QuestPDF · FluentValidation · Serilog

Cloud & Delivery

Azure App Service · Azure SQL · Azure Blob · Docker · GitHub Actions CI/CD · Git

CAREER TIMELINE

Apr 2026 — Present

Software Engineer (BMS Lead)

VaatcoBMS · Sole software engineer responsible for domain modeling, architecture, and deployment of manufacturing ERP and double-entry ledger.

Jul 2024 — Mar 2026

Junior Software Engineer

Devsfair · Built REST APIs, Blazor components, and automated test suites for fintech and data integration platforms under senior mentorship.

Dec 2023 — Jun 2024

Backend Developer Intern

Devsfair · C# ASP.NET Core APIs, Dapper CQS data access routines, and Azure Blob storage integration.

EDUCATION

B.Sc. in Computer Science and Engineering

East West University · Dhaka, Bangladesh

Graduated Nov 20234-Year Degree

LET'S TALK / DHAKA, BANGLADESH

Dealing with a messy workflow, or looking for a developer who cares about how the business works?

Whether you're trying to untangle inventory, billing, and daily operations in your business, or building a team that values thoughtful, dependable software—I’d love to chat.

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