Lima, Peru · Software Engineering, UPC

Backend Developer · .NET

Mathias Jave Diaz

I design secure, scalable REST APIs with ASP.NET Core and Azure for the fintech sector.

1 min: average transfer time in WebFX (Western Union)
30: critical/high vulnerabilities remediated (Checkmarx)
5 min → 50 s: accounting book generation time

developer.ts

const developer = {
  name: "Mathias Jave Diaz",
  university: "UPC",
  stack: ["C#", ".NET", "Azure", "SQL Server"],
  focus: ["Fintech", "Applied AI", "Security"],
  status: "currently employed",
};

About me

I build secure backends for financial operations: APIs, payment gateways and identity.

I'm Mathias, a Software Engineering graduate from UPC with over 2 years building enterprise applications. Today I work at Western Union (assigned through ITSIGHT Consulting), where I develop and maintain REST APIs in ASP.NET Core (.NET 8) for payments, currency exchange and accounting.

I care about software that holds up in production and stays secure: I design with Hexagonal and layered architecture, handle identity and access with Okta, CyberArk and RBAC, and deploy on Azure and Docker. I've migrated 8 legacy Visual Basic .NET modules to .NET 8 and, at Hiperfast, automated the search for ISO 17020 inspection reports, from weeks down to 10 seconds per certificate.

I'm also researching how AI can prevent fraud: my thesis, ScamShield, uses Machine Learning and NLP (DistilBERT) to estimate scam risk in online purchases and was accepted for presentation at BTSym 2026. I want to keep growing in banking and fintech, where backend, security and applied AI meet.

Download CV

+2 years in enterprise applications
BTSym 2026 research paper accepted
Western Union current client
Spanish · English B1 languages

02 / Experience

Experience

Building and securing web applications for the financial sector and for accredited inspection bodies.

01
Western Union (assigned through ITSIGHT Consulting)

Junior Software Engineer · Lima, Peru

Feb 2025 - Present
Key results
- Reduced the average WebFX transfer time to 1 minute per operation by integrating the Ligo API into a centralized payment-provider API, itself integrated into WebFX.
- Remediated 30 critical and high vulnerabilities reported by Checkmarx in the Poseidon Peru project, avoiding delays in the production release.
- Cut accounting book generation time from 5 minutes to 50 seconds per book.
- Successfully migrated 8 Visual Basic .NET modules to .NET Core 8 in the accounting and tax area, handling accounting books with over 1,000 records.
- Automated traceability reports for grouping accounting entries.
Responsibilities (10)
- Design and development of REST APIs in ASP.NET Core (.NET 8) using Hexagonal, MVC and layered architecture.
- System integration through REST APIs with external payment gateways (Ligo and Pago Efectivo), with custom middleware and automated billing flows.
- Implementation of authentication and authorization with identity providers (Okta, CyberArk) and role-based access control (RBAC).
- Traceability through logging to monitor and detect incidents in production and non-production environments.
- Use of Azure services in production applications: Blob Storage, Key Vault, App Service and Azure Database for MySQL.
- Maintenance of the WebFX project for web-based currency exchange, with a scalable architecture applicable globally.
- Maintenance of back-office applications with progressive .NET upgrades (5, 8 and 10) under Microsoft LTS policies, and optimization of business rules through SQL Server stored procedures.
- Migration of legacy Visual Basic .NET modules to .NET Core 8, ensuring compatibility and performance.
- Data flows and ETL processes with SQL Server and SSIS for accounting information processed by globally distributed teams.
- Requirements gathering and follow-up meetings with stakeholders to ensure technical alignment.
- C#
- ASP.NET Core (.NET 8)
- SQL Server
- SSIS
- Azure
- Okta
- CyberArk
- RBAC
- Checkmarx
- Hexagonal Architecture
02
Hiperfast SAC

FullStack Developer · Callao, Peru

Jul 2024 - Jan 2025
Key results
- Automated the search for technical inspection reports, reducing the time from weeks to 10 seconds per certificate.
Responsibilities (4)
- Development of web systems for ISO 17020 certificate validation and invoice control with a layered architecture in .NET Core 8 and MySQL.
- Containerization with Docker and production deployment setup, ensuring high availability and portability.
- MySQL query optimization, reducing response times and ensuring transactional integrity in critical operations.
- Technical risk assessment and implementation of security measures in production environments.
- C#
- .NET Core 8
- MySQL
- Docker

03 / Projects

Projects

A selection of client, thesis and academic work, prioritizing fraud prevention, payments and architecture.

Thesis · BTSym 2026
Featured project
ScamShield — Scam prevention for online purchases with ML and NLP

Distributed fraud-prevention solution for e-commerce that estimates scam risk probability with Machine Learning and NLP (DistilBERT fine-tuning with PyTorch/Transformers), deployed on Azure.
- .NET Core
- Flask
- Next.js
- MySQL
- Machine Learning
- DistilBERT
- Azure
View project
Client · UDEP
Amigos UDEP Scholarship Fund — Donation platform

Donation platform with online payments through Niubiz, donation certificates stored in Azure Blob Storage, an admin dashboard with Azure AD authentication, email delivery via Microsoft Graph and reCAPTCHA.
- ASP.NET Core 8
- Clean Architecture
- Next.js
- Oracle
- Niubiz
- Azure
- xUnit
View project
Client · YAVA S.A.C.
YAVA — Corporate website

Corporate site for a fuel transport and distribution company with 39 years in the market: services, clients, policies and a contact form backed by Azure Functions, deployed on Cloudflare with CodeQL analysis in the pipeline.
- Astro
- TypeScript
- Tailwind CSS
- Cloudflare Workers
- Azure Functions
- GitHub Actions
View project
Client · FLUX Tecnología
FLUX Tecnología — Industrial product catalog

Web catalog for an importer of industrial machinery and automotive urea, with filters, search and WhatsApp quotes, plus a React admin panel for product CRUD. Serverless backend on Azure Functions over Firestore and Cloudinary, with Firebase authentication and continuous deployment to Cloudflare Pages.
- JavaScript
- React
- Azure Functions
- Node.js
- Firestore
- Firebase Auth
- Cloudinary
- Cloudflare Pages
- GitHub Actions
View project
Client · HIPERFAST S.A.C.
Invoice Validation and Control

Invoice validation and control system for an inspection body with ISO 17020 accreditation, featuring state management and consumption charts.
- C#
- .NET
- Vue.js
- MySQL
- Docker
- Clean Architecture
Client · CORSERSAC S.A.C.
Report Validation

Certificate of conformity validation system for an ISO 17020 accredited body, with customer management features.
- C#
- .NET
- Vue.js
- Node.js
- MySQL
View project
Freelance
Maintenance Sheets — Activity logging and automated reports

Mobile app that replaces the paper maintenance field sheet: technicians look up equipment by code, record the person in charge, a description and photos, and a PDF is generated and stored in Google Drive, with an offline queue. I also built a Make automation, integrating the Google Drive and Google Sheets APIs, that fills in the information daily to produce valuable reports from the activity records.
- Flutter
- BLoC
- Clean Architecture
- Google Apps Script
- Google Drive API
- Google Sheets API
- Make
Freelance
Attendance control with facial recognition

Mobile app that records employee attendance with on-device facial recognition (ML Kit detection and MobileFaceNet embeddings on TensorFlow Lite) and a FastAPI REST API with MySQL for registration and history, covered by unit, integration and API tests.
- Flutter
- BLoC
- TensorFlow Lite
- ML Kit
- FastAPI
- SQLAlchemy
- MySQL
- Docker
- Pytest
UPC course · Mobile Applications
Event Space Rental App

Platform with reservation management, payment integration, and a review system. Robust architecture focused on business scalability.
- Flutter
- C#
- Firebase
- PayPal
- CQRS
- DDD
UPC course · Experiment Design
MoviRent — Electric scooter rental

Platform connecting electric scooter owners with renters, built with Experiment-Driven Development: hypotheses, experiment cards, A/B testing and BDD with Gherkin.
- Vue.js
- Flutter
- Docker
- PostgreSQL
- Render
- Gherkin
Personal project
Vivlo

Artificial Intelligence assistant focused on accompanying and caring for patients with diabetes, using foundational cloud models.
- Flutter
- .NET Core
- AWS API Gateway
- AWS Lambda
- AWS Bedrock
UPC course · 7-person team
EcoGuardian

IoT solution for agricultural monitoring with real-time alerts, personalized recommendations, and a distributed architecture.
- ASP.NET Core
- Vue.js
- Flutter
- IoT
- Stripe
- Docker
View project

04 / Stack

Tech stack

The tools I use to build reliable, secure and scalable applications.

Backend

C#
.NET Core / ASP.NET Core
.NET Framework
APIs REST
Python (Flask)
Node.js
xUnit
NUnit

Architecture

Hexagonal
Microservices
Layered
MVC
Modular Monolith
DDD
SOLID
Clean Code

Cloud (Azure)

Blob Storage
Key Vault
App Service
Azure Database for MySQL
Functions
Container Apps
Azure SQL

Security & identity

Okta
CyberArk
Auth0
RBAC
OWASP Top 10
Checkmarx

Databases

SQL Server
Azure SQL
MySQL
PostgreSQL
MongoDB
DynamoDB
Supabase
Oracle Db

DevOps & tools

Azure DevOps
CI/CD
Docker
Git
GitHub
Linux (bash)
Postman

Frontend

JavaScript
React
Next.js
Angular
HTML
CSS
Bootstrap

ETL & data

SSIS
Pandas
Power BI

AI & ML

Machine Learning
FineTuning
PyTorch
Transformers
Scikit-learn

AI-assisted development

Claude Code
OpenCode
Antigravity CLI

Methodologies

Scrum (SFC)
Kanban

05 / Training

Education & certifications

Academic background, research, certifications and awards that complement my production work.

Bachelor in Software Engineering (degree in process)

Universidad Peruana de Ciencias Aplicadas (UPC) · Lima

Mar 2022 – 2026 · Graduate, bachelor's degree in process

Thesis: “Estimating Scam Risk Probability in Digital Purchases”: a distributed fraud-prevention solution for e-commerce with Machine Learning and NLP (DistilBERT fine-tuning with PyTorch/Transformers); .NET Core / Flask backend, Next.js frontend, MySQL; deployed on Azure (Container Apps, Functions, Azure Database for MySQL).
Publication: Jave Diaz, M. A., Avila Asto, A. & Garcia Rojas, F. (2026). “Before the Click: Client-Side Analysis to Mitigate Scam Risk Probability in Digital Purchases”. Accepted for presentation at BTSym 2026.