Bang Nguyen
Verified Expert in Engineering
Software Developer
Houston, TX, United States
Toptal member since February 28, 2025
Bang is a senior software engineer with 15 years of experience designing and developing large-scale applications using Jakarta EE, Spring Framework, and SOA. As a full-stack developer, he specializes in Java, JavaScript, REST APIs, and Spring. Skilled in writing complex SQL queries using ORM frameworks such as Hibernate and Java Persistence API (JPA) to optimize database performance, Bang excels at understanding client needs to produce quality software and foster strong relationships.
Portfolio
Experience
- Java - 15 years
- MySQL - 15 years
- Spring - 15 years
- JavaScript - 10 years
- MuleSoft Anypoint Platform - 8 years
- Hibernate - 8 years
- REST APIs - 8 years
- Angular - 3 years
Availability
Preferred Environment
Linux, Visual Studio Code (VS Code), Eclipse IDE
The most amazing...
...thing I've done is lead the tech stack decision and build Spring Boot microservices from the ground up for a doctor/patient calendar scheduling application.
Work Experience
Full-stack Developer
Freelance Client
- Converted an eCommerce website from JSP/Struts to a modern React front end using TypeScript and Tailwind CSS, with an Express.js back end using TypeORM and REST APIs to enhance the site's performance, user experience, and maintainability.
- Modified and optimized PostgreSQL database queries to ensure better performance and user experience.
- Monitored and addressed bugs reported by the site owner, ensuring timely resolution of issues to maintain optimal website performance.
Senior Software Engineer
Sophists Solutions
- Developed Spring Boot microservices for a doctor and patient calendar scheduling app using AWS Kinesis for event sourcing and real-time data stream processing. Built REST APIs for communication between client- and server-side components.
- Created Spring Boot microservices to facilitate medical staff enrollment to facilities and manage doctor and patient information, leveraging the Fast Healthcare Interoperability Resources (FHIR) REST API for interoperability and data exchange.
- Designed and implemented MuleSoft ESB service components to support email delivery using SendGrid API and the management of credential documents using Amazon S3 storage with Active MQ for queuing and failover.
- Developed ETL tools in Node.js to integrate medical provider data from MySQL, APIs, and CSV. Updated user records and linked them to medical facilities.
- Developed reporting tools in Node.js to generate CSV reports tracking medical provider enrollment status, with logging to facilitate troubleshooting.
- Implemented YAML configurations for Helm charts to streamline the deployment of Spring Boot microservices within Docker containers. Automated CI/CD pipelines to ensure seamless integration and deployment.
- Integrated SonarQube into the CI/CD pipeline to enforce code quality standards and conducted peer code reviews to ensure quality and best practices.
Full-stack Developer
KaiTaiR
- Developed full-stack single-page applications for a web booking engine and a multi-tenant hotel supplier management system utilizing AngularJS for the front end and Spring, REST, Hibernate, and MySQL for the back end.
- Led the implementation of a MuleSoft ESB to integrate bookings, availability, rates, and property content between the company's central reservation system and travel distribution partners like Booking.com and Expedia.
- Managed integration projects with the off-shore development team in India by designing solutions, delegating tasks, and ensuring project timelines were met. Conducted peer code reviews to ensure quality and best practices.
- Automated CI/CD pipelines using Maven-based scripts for application builds and deployments and, in addition, managed QA and production environments to ensure reliable deployments and optimal system performance.
Experience
Medical Staff and Patient Enrollment Application
• Creating a WSO2 user account, a personal or shared calendar for scheduling appointments, and staff or patient data in an FHIR server using FHIR REST APIs.
• Sending email notifications to complete registration, such as changing a one-time password.
This implementation reduced manual effort, improved data accuracy, and accelerated the onboarding process of medical staff and patients.
Hotel Booking and Supplier Management System
As a full-stack developer, I transformed UX design prototypes into fully functional web applications using AngularJS to build responsive front-end interfaces. I designed and implemented high-performance systems using Spring Framework on the back end. Hibernate performance was optimized by writing complex SQL queries and implementing Ehcache for rates and availability lookup, reducing response times by 70%.
ESB Integration for Central Reservation System and Online Travel Agencies
• Viewing and managing bookings (from partner online travel agencies, such as Booking.com) by property managers in their central reservation system application.
• Maintaining availability, inventory, rates, and property images/content in the property manager's central reservation system and uploading the data to the partner online travel agencies.
As the lead developer, I gathered requirements from each online travel agency partner, designed the integration workflows, and implemented the Java-based components and connectors in the MuleSoft platform, leveraging SOAP or REST APIs based on the partner's protocol.
Skills
Libraries/APIs
Node.js, Java Message Service (JMS), SOAP APIs, OpenAPI, REST APIs, React, Jenkins Pipeline, SendGrid API, jQuery
Tools
Apache Maven, GitHub, Eclipse IDE, Bitbucket, SonarQube, ActiveMQ, Apache Tomcat, Jira, SonarCloud, Helmfile, Subversion (SVN), Git, Jenkins
Languages
JavaScript, Java, XML, HTML, SQL, CSS, TypeScript
Frameworks
Spring Boot, iBATIS, Hibernate, Spring 3, Spring 4, Spring 5, Angular, Spring MVC, Spring, Spring Microservice, Express.js, Apache Struts 2, Spring Security, JSON Web Tokens (JWT), Bootstrap 3, Tailwind CSS
Paradigms
REST, Fast Healthcare Interoperability Resources (FHIR), Microservices, ETL, HL7 FHIR Standard
Platforms
Eclipse, Mule ESB, Docker, Apache Kafka, Linux, Visual Studio Code (VS Code), Amazon Web Services (AWS), Kubernetes, AWS Lambda
Storage
MySQL, Spring Data JPA, JSON, Amazon S3 (AWS S3), PostgreSQL, MongoDB, SQL Server 2012, Amazon DynamoDB
Other
MuleSoft Anypoint Platform, Hibernate 3, SOAP, RESTFul APIs, APIs, RESTful Microservices, RESTful Web Services, Back-end, Amazon Kinesis, WSO2 API Manager, Ehcache, WSO2, Bootstrap 5, CI/CD Pipelines, TypeORM, Quarkus
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