Open to opportunities

Hai Nguyen

@hainguyen1

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Senior backend engineer specializing in C#/.NET, Oracle, and MongoDB for enterprise systems.

Vietnam

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What I'm looking for

I seek remote freelance/contract backend or senior full-stack roles with international teams, ownership of projects, and long-term collaboration.

I am a Senior Software Engineer with 12+ years building and maintaining enterprise systems across banking, telecom VAS, and large-scale business platforms. I specialize in backend development using C#/.NET, Oracle Database, and MongoDB, focusing on reliability, performance, and maintainability.

My experience includes developing card core and transaction processing systems for a major bank, building backend features and APIs for an education management platform, and implementing high-volume telecom VAS and SMS services. I routinely collaborate with product owners and non-technical stakeholders to clarify requirements and deliver stable production-ready solutions.

I am open to remote freelance or contract roles and long-term collaboration with international teams, where I can take ownership, improve system stability, and deliver scalable backend solutions.

Experience

Work history, roles, and key accomplishments

Current

Software Developer

Current

OWNA

Mar 2023 - Present (2 years 11 months)

Developed and maintained backend features for an education management platform used by thousands, building C# APIs and MongoDB data models while improving system stability and performance.

C++.NET MongoDB REST APIs Backend Development Performance Tuning CI CD Agile

Software Engineer

MB Bank

May 2016 - Mar 2023 (6 years 10 months)

Developed and supported Card Core systems including transaction processing and card management, implementing complex business logic in Oracle/PLSQL and ensuring high production reliability.

Oracle Pl SQL C++Transaction Processing Performance Optimization Data Optimization

Software Developer

OSP Group

Mar 2014 - Mar 2016 (2 years)

Implemented backend features for telecom VAS including SMS services, subscription management, and billing flows, handling high-volume transactional data with Oracle.

Oracle SMS Subscription Management Billing Backend Development Telecom VAS

Software Developer

NEO Jsc

Jun 2012 - Feb 2014 (1 year 8 months)

Worked as a junior developer on telecom VAS projects, implementing SMS-based services and subscription handling while supporting production systems using PHP and Oracle.

PHP Oracle SMS Backend Development Junior Development

Education

Degrees, certifications, and relevant coursework

VNU University of Engineering and Technology

Bachelor's degree, Information Technology

2008 - 2012

Completed a Bachelor's degree in Information Technology with coursework and projects focused on software development and backend systems from September 2008 to June 2012.