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Senior Software Engineer · Vision33 · Since 2015

I build enterprise systems the business stops worrying about.

Eleven years designing reliable software on one mission-critical platform — ERP integration, financial automation, and cloud architecture. I design for correctness first, and I build systems that earn trust and keep it.

See the evidence → How I think mahmud.sust@gmail.com
Mohammad Hassan Mohammad Hassan
11 yrs
One platform, made better every year
Production
Money-moving systems, unattended
Azure + AWS
Cloud architecture & integration
IC → Architect
Individual work to technical leadership

What I’ve come to believe

A decade of shipping teaches you what actually matters. These are the convictions I build on.

01

Correctness is a design decision, not a testing phase.

When code moves money, a duplicate invoice isn’t a bug ticket — it’s a customer-facing financial error. So I design for the failure case first: idempotent runs, replay-safe state, systems that fail without lying. Reliability isn’t bolted on at the end. It’s the shape of the thing from the start.

Evidence · Automated Billing & Tax Engine →
02

The best system is the one nobody has to think about.

Good architecture disappears. I build integration platforms that hum in the background — partners and staff get exactly what they need, the system of record stays protected, and no one files a ticket. Point-to-point sprawl is easy to start and impossible to maintain; a real platform grows in straight lines, not tangles.

Evidence · ERP Integration Platform →
03

Trust should be provable, not requested.

The strongest systems don’t ask to be trusted — they let you verify. In a privacy-preserving prescription protocol, a pharmacy can confirm a prescription is legitimate without ever learning who wrote it. That’s the aim everywhere: make the guarantee checkable, so trust never has to rest on faith.

Evidence · Secure NFC e-Prescription →
04

Correlation is cheap. Conclusions are earned.

Before I believe a result, I try to break it. Modeling osteoarthritis biomarkers, the easy answer — what correlates — is usually the wrong one; the real question is what drives the outcome, cross-validated until it survives scrutiny. I bring that same skepticism to production. A number I can’t defend is a number I don’t ship.

Evidence · Metabolomic Biomarkers →

The evidence

Four problems where the hard part wasn’t the code.

Enterprise finance, integration architecture, applied cryptography, and causal inference. Each written up honestly — context, constraints, and the trade-offs I chose.

  1. Integration Architecture 2016 – Present

    ERP Integration Platform

    The ERP stays the single system of record. Everything else is a projection of it — protected, and available 24/7.

    • .NET Core
    • C#
    • SAP Business One
    • Saltbox
    Read the case →
  2. Financial Automation 2016 – Present

    Automated Billing & Tax Engine

    This code moves money. A duplicate invoice isn't a bug ticket — it's a customer-facing financial error.

    • C#
    • .NET Worker Services
    • Avalara AvaTax
    • SAP Business One
    Read the case →
  3. Applied Cryptography Master's thesis

    Secure NFC e-Prescription System

    A pharmacy can fully trust the prescription without ever learning who wrote it.

    • Proxy signatures
    • Short group signatures
    • NFC
    • Mobile
    Read the case →
  4. Data Science & Causal Inference Graduate research

    Metabolomic Biomarkers for Osteoarthritis

    The question was never what correlates with the disease — but what plausibly drives it.

    • Bayesian networks
    • Structural equation modeling
    • Path analysis
    • Multiple regression
    Read the case →

The eleven-year arc

One platform. Rebuilt underneath the business, without stopping it.

Most engineers change jobs to grow. I grew by staying — taking one business-critical platform and modernizing it continuously while it ran the company. The stack changed completely. So did my role.

.NET Framework
→ .NET Core
On-premises
→ Azure & AWS
Manual finance ops
→ Automated billing
Writing features
→ Architecting platforms

Vision33 · 2015 – Present · Remote, Montreal QC

  1. Apr 2025 – Present

    Senior Software Developer

    • Architecture
    • Mentorship
    • Technical advisory
    • Lead design and development of internal .NET Core web platforms (Partner and Employee portals) providing secure, 24/7 web access to SAP Business One data.
    • Architect integration workflows on the Saltbox platform, connecting ERP, HR, and finance systems across SQL Server, Azure, and AWS to eliminate data silos.
    • Own automated financial features — auto-invoicing, recurring billing, and data migration — built on C#, .NET, and cloud functions, including Avalara AvaTax integration.
    • Serve as senior technical advisor; mentor junior developers and champion CI/CD and agile practices across the team.

  2. Jul 2016 – Mar 2025

    Software Developer

    • IC
    • System ownership
    • Built and owned internal .NET Framework and .NET Core applications for HR and finance workflows, integrated with SAP Business One.
    • Implemented automated invoicing, custom reporting, and recurring background services using C#, ASP.NET MVC/Core, SQL Server, AWS, and Azure.
    • Delivered integration services for third-party APIs, including Smartsheet and Avalara AvaTax.
    • Migrated legacy applications to modern platforms — upgrading to .NET Core and deploying to the cloud.

  3. Aug 2015 – Jun 2016

    Intern & Part-Time Developer

    • IC
    • Contributed C# features to .NET Framework applications; assisted with SQL Server and external API integrations, gaining first Azure and AWS deployment experience.

In my own words

I’m Mohammad — an engineer who spent a decade making one system more trustworthy, and still gets a quiet thrill the moment a hard problem finally goes calm.

I care about correctness, clarity, and building software that outlasts the hype cycle — and I keep learning whatever tools that takes. I’m most useful where the stakes are real, the systems are tangled, and someone needs to make them dependable.

Let’s talk.

Open to senior and staff engineering roles, and to interesting problems in reliable, large-scale software.

Email mahmud.sust@gmail.com → Résumé The one-page version →

Based in Montreal, QC · Available remotely