Sung is available for hire
Hire SungSung Hyun Back
Verified Expert in Engineering
Software Developer
Toronto, ON, Canada
Toptal member since January 14, 2026
Bio
Sung Hyun is a versatile senior software engineer with 9+ years of experience building production-grade software and automation solutions. His expertise spans full-stack, back-end, API, native Android, cross-platform development, and workflow automation. Sung Hyun combines broad engineering expertise with AI-assisted development to accelerate implementation, testing, and engineering workflows while delivering reliable, scalable software.
Portfolio
HP Inc
Android App Development, Back-end Development, Workflow Automation...
Mapsted
Android App Development, Software Engineering, Application Engineering
The ARIES Inc.
Android App Development, Back-end Development, API Development...
Experience
- Application Engineering - 9 years
- Full-stack Development - 9 years
- Software Engineering - 9 years
- Android App Development - 9 years
- Back-end Development - 6 years
- Workflow Automation - 6 years
- API Development - 6 years
- System Integration - 6 years
Preferred Environment
Android App Development, Full-stack Development, Back-end Development, Workflow Automation, API Development
The most amazing...
...thing I've built is software in diverse domains, from consumer products and back-end systems to full-stack applications and automation, using AI to ship faster.
Work Experience
Software Applications Engineer
2021 - PRESENT
HP Inc
- Contributed to the HP Workforce Experience Platform by developing back-end services for the Device Settings Management component, enabling device configuration, policy enforcement, and large-scale enterprise deployments.
- Developed and maintained event-driven processing pipelines using Java, Spring Boot, AWS Lambda, SQS, SNS, and RabbitMQ, supporting high-volume device management workflows and improving platform scalability.
- Optimized back-end performance through MongoDB query tuning, indexing strategies, schema migrations, and REST API improvements.
- Improved observability by maintaining Splunk log pipelines and implementing Datadog dashboards, alerting, monitoring, and operational metrics.
- Developed workflow automation solutions using Microsoft Power Automate, AI agents, Jira integrations, and internal tooling, reducing manual operational effort and streamlining engineering processes.
- 𝗔𝗻𝗱𝗿𝗼𝗶𝗱 - Developed and maintained the Android SDK for the HP Roam platform, delivering secure cloud printing capabilities to the HP app (100+ million downloads) and HP Roam applications.
- Developed and enhanced core SDK features for print workflows, device discovery, and cloud communication using Kotlin, Coroutines, Bluetooth LE, Firebase Cloud Messaging, MVVM, Jetpack Compose, and Android SDK.
- Led architectural modernization initiatives across legacy MVP and new MVVM architectures, supporting Android 9 through Android 15.
- Owned CI/CD, release management, and SDK distribution through Azure DevOps, GitHub, and Nexus Repository, ensuring reliable delivery of production-ready releases.
- Developed workflow automation solutions using Microsoft Power Automate, Jira APIs, and internal tooling to streamline issue management, application delivery workflows, and team operations.
Technologies: Android App Development, Back-end Development, Workflow Automation, Software Engineering, System Integration, Java, Kotlin, Jetpack Compose, Model View ViewModel (MVVM), Spring Boot, API Development, Python, Microsoft Power Automate
Intermediate Android Developer
2020 - 2021
Mapsted
- Contributed to Mapsted’s indoor navigation and location-intelligence platform, supporting deployments across malls, campuses, and museums, including Dubai Mall, Square One, and the University of Windsor.
- Developed and enhanced multiple Android SDK libraries and applications delivering real-time indoor positioning, navigation, and location intelligence capabilities using Java, Retrofit, OkHttp, XML, and Android SDK.
- Managed SDK release cycles and artifact distribution through JFrog Artifactory, Git, and Gradle, ensuring consistent delivery and versioning across internal and partner-facing integrations.
- Authored and maintained technical documentation, API references, and integration guides, improving developer onboarding and SDK adoption.
Technologies: Android App Development, Software Engineering, Application Engineering
Software Development Manager
2019 - 2021
The ARIES Inc.
- Developed an Android-based point-of-sale system sold through Amazon and Costco Canada, achieving 100+ units sold within four months and ranking among the Top 5 products in Amazon.ca’s Point-of-Sale category.
- Architected and developed the Android application and core POS functionality using Kotlin, Coroutines, MVVM, Retrofit, OkHttp, Room, Dagger/Hilt, and Bluetooth, enabling reliable transaction processing and device-to-device communication.
- Designed a modular multi-module architecture, applying modern Android design principles to improve maintainability and support future feature expansion.
- Built back-end services using Python, Django, MySQL, Rest APIs, and JSON-based communication, supporting secure data storage, transaction processing, and seamless integration with the Android application.
Technologies: Android App Development, Back-end Development, API Development, Application Engineering, Software Engineering, System Integration, Python
Full-stack Software Developer
2016 - 2019
HEXA Electronics
- Developed a production-ready eCommerce platform supporting real-time ordering across the company’s retail and hospitality devices. Owned the full development lifecycle, delivering a scalable and reliable ordering experience.
- Designed and developed the platform using React, TypeScript, Node.js, Express, REST APIs, and PostgreSQL, enabling real-time ordering and order management functionalities.
- Architected scalable front-end and back-end components supporting reliable communication between client applications and back-end services.
- Built responsive user interfaces using RxJS and Material UI while optimizing real-time ordering workflows for retail and hospitality environments.
- Contributed to Restaurant Hub, an Android-based food-ordering platform for restaurants, hotels, and resorts, showcased at the Restaurant Canada trade show and the HEXA CN Tower event.
- Developed and delivered three Android applications supporting guest, kitchen, and management workflows using Java, Android SDK, XML, and Android UI components.
- Designed and implemented real-time communication capabilities using TCP/ IP socket programming, Android Services, BroadcastReceiver, and background processing, enabling reliable order synchronization and device-to-device interactions.
- Defined communication standards and XML-based data structures across multiple system modules, improving platform consistency and simplifying future development.
Technologies: Android App Development, Full-stack Development, Web Development, Software Engineering, Application Engineering
Experience
Android SDK Libraries and AI-driven Android App Development
https://github.com/sung2063/AndroidSliderViewsLibraryI developed multiple open-source Android SDK libraries, including a carousel UI component and a Bluetooth communication module, along with sample apps that streamline developer integration. I also built a native Android application that integrates TensorFlow Lite to analyze skin-lesion images and identify potential cancer risks. I designed a complete on-device ML inference pipeline, optimized model performance for mobile, and delivered a smooth, intuitive user experience through efficient image preprocessing, camera handling, and clear result visualization.
Dining‑QR: Restaurant Ordering System (Full‑stack)
https://github.com/sung2063/dining-qr-ordering-frontendDining-QR is a restaurant ordering system that lets guests scan a QR code to browse the menu and place orders directly from their smartphones. It also includes a management dashboard for handling tables, staff, menu items, and real-time orders. The platform enhances the dining experience for customers and provides restaurant owners with practical tools and insights to manage operations more efficiently. The back end was built with Java, Spring Boot, and MySQL, and the front end uses React and TypeScript, with an optional Flutter mobile version.
Multi‑company Website Development (WordPress and Custom Web)
I developed and maintained websites for multiple companies, including Petroff Architecture (custom site development), Spectrum Mechanical (WordPress), and HEXA Electronics (WooCommerce). Worked across both front‑end and back‑end development using HTML, CSS, JavaScript, jQuery, PHP, and WordPress, and supported ongoing updates, content management, and site maintenance.
Education
2013 - 2017
Bachelor's Degree in Mathematics and Computer Science
York University - Toronto, ON, Canada
Certifications
APRIL 2023 - APRIL 2025
Google Play Store Listing Certificate
Google for Developers
APRIL 2021 - APRIL 2024
Associate Android Developer
Google for Developers
Skills
Libraries/APIs
API Development, React, Node.js
Languages
Java, TypeScript, Kotlin, Python
Platforms
Microsoft Power Automate
Frameworks
Spring Boot
Paradigms
Model View ViewModel (MVVM)
Other
Android App Development, Full-stack Development, Back-end Development, Application Engineering, Software Engineering, Workflow Automation, System Integration, Applied Mathematics, Cross-Platform Mobile Development, Web Development, Jetpack Compose
Collaboration That Works
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
1
Share your needs
Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2
Choose your talent
Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3
Start your risk-free talent trial
Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.
Top talent is in high demand.
Start hiring