Harry Sun
Verified Expert in Engineering
Java Developer
Melbourne, Victoria, Australia
Toptal member since December 13, 2014
Harry is a senior GenAI and full-stack engineer with 28+ years of experience in Java, Python, TypeScript, and cloud technologies. He bridges the gap between AI prototypes and production services. Recently, he has focused on applied LLM delivery, including RAG, AI search, and human-in-the-loop workflows for insurance and CRM. Through OpenClaw research, Harry transforms complex projects into autonomous, closed-loop systems with robust API boundaries, observability, and production guardrails.
Portfolio
Experience
- Java - 10 years
- Generative Artificial Intelligence (GenAI) - 6 years
- Amazon Web Services (AWS) - 3 years
- Python - 3 years
- TypeScript - 3 years
- Large Language Models (LLMs) - 3 years
- Lovable - 1 year
- Supabase - 1 year
Preferred Environment
Amazon Web Services (AWS), Java, Lovable, Supabase, n8n, OpenClaw, ClaudeCode, Python, Google Cloud Platform (GCP), Large Language Models (LLMs)
The most amazing...
...thing I've done is create an autonomous workflow in OpenClaw, allowing me to compete in the Kaggle AI Mathematical Olympiad - Progress Prize 3 in 10 days.
Work Experience
Solution Architect
Ayla
- Owned solution architecture for a portfolio of applied-AI services across bill extraction, personal finance chat, eCommerce search, real estate listing workflows, AI-assisted CRM, and insurance claim automation.
- Led the bill extraction migration from AutoML/Document AI and vendor-specific parsing to LLM-powered extraction, improving accuracy from roughly 78% to about 95% and reducing new supplier bill integration from five days to one day.
- Implemented a staged GenAI CRM pipeline for a real estate admin portal, transforming emails, screenshots, and email threads into issues, solution plans, draft replies, FAQ candidates, customer memory, and stage-level diagnostics.
- Maintained the core API and integration platform behind these workflows, covering billing, document processing, notifications, cloud storage, provider APIs, validation, deployment, and operational guardrails.
- Built AI search and listing automation components, including hybrid semantic/keyword product retrieval, WooCommerce index synchronization, marketplace listing generation, and GPT-assisted real estate XML normalization.
Senior Software Engineer
Directed Electronics Australia
- Architected and built a beacon server for senior-care pendant tracking and monitoring using Java 17, Spring Boot, Netty, Redis, RabbitMQ/AMQP, MQTT, and PostgreSQL.
- Refactored beacon server to use stream queues, which improved overall performance by 50% in EC2 update and OTA process, and increased concurrent device volume from around 5,000 to around 20,000 on a typical t3 small EC2 instance.
- Built Balena Cloud and Open Balena, an open-source solution for containerizing IoT devices on the cloud.
- Created a few website/demo side projects from scratch, based on AWS API Gateway, Lambda, CloudFront, React, Redux, Saga, and Ant Design. Trained team members and managed projects.
- Managed an offshore team on a few projects, including APIs (Java, Spring Boot, and jOOQ), mobile apps (React Native), and admin consoles (React and Ant Design).
Senior Software Engineer
Odecee (Cognizant)
- Developed a product recommendation microservice from scratch using JDK11 and a rules engine for a project at ANZ.
- Created a microservice product for small businesses at ANZ utilizing Java, Spring, Spring Boot, Apache Camel, React, Redux, Saga, and OpenShift.
- Built the BOX and SBOLA projects using Java/Spring Boot microservices and a Groovy/Spock rules engine for product recommendation and retail banking workflows, integrating Hibernate, Redis, Apache Camel, OpenShift, React, Redux, Jest, and Cucumber.
Software Engineer
IRESS
- Created and implemented a TypeScript code analysis tool to generate API document and enforce coding rules in the data layer.
- Designed and implemented widget plugins, item picker, account picker and account explorer, and portfolio picker. The account picker and explorer can support loading 110,000 accounts.
- Designed and developed the search feature/component in the front end.
- Built the data layer for a notification and alert feature.
- Improved security and performance of the application, also enhanced the deployment tool using C# and .NET.
Contractor Developer
Epictenet
- Resolved a blocker issue by using AM/VO instead of REST URL data control to deal with complex scenarios in ADF in my first two weeks on this project.
- Worked out all functions of my documents by using a library based on RIDC protocol to access a UCM file repository at the back end and ADF task flows with beans at the front end.
- Improved the UI framework. Continuously constructed some handy utility classes to handle mapping between POJO and JSON based on Apache BeanUtils and Jettison.
- Introduced a straightforward and flexible approach to call RESTful APIs through the ADF front end.
Project Lead, Development Manager
Oracle (China) Software Systems Co., Ltd.
- Designed, developed, and maintained the Fusion HCM payroll Australia localization on several hands-on UI and reporting projects.
- Managed a sample implementation project for Fusion HCM HR and payroll China localization using a scrum approach and operating as scrum master.
- Received an employee recognition award in May 2013.
Experience
Machine Learning
https://github.com/harrysun2006/17_machine_learningNeural Network for Machine Learning
https://github.com/harrysun2006/17_neural_networksDemo Portal for SalaryMaster Corporation
Website for EquityMaster
Idea System (J2EE)
An Evaluator (Flash ActionScript)
Education
Advanced Degree in Mathematics
Nanjing University - Nanjing, China
Certifications
Neural Networks for Machine Learning
University of Toronto | via Coursera
Machine Learning
Stanford University | via Coursera
Skills
Libraries/APIs
JOOQ, React, jQuery, Node.js, jQuery UI, JAX-RS, Google API, Google Maps
Tools
Docker Compose, JDeveloper, Oracle Business Intelligence Enterprise Edition 11g (OBIEE), Gradle, Microsoft Visual Studio, n8n
Languages
TypeScript, Java, JavaScript, SQL, Python, Rust, XML, Sysl, C, PowerBuilder, C++, Flash ActionScript
Frameworks
Netty, JPA, ADF, Spring, JUnit, Jersey, Spring Boot, Knockout (Knockout.js), Redux, Camel
Platforms
Amazon Web Services (AWS), Docker, Oracle, Google Cloud Platform (GCP), Jakarta EE (Java EE or J2EE), WebCenter
Storage
PostgreSQL, Oracle PL/SQL, Redis, MongoDB
Paradigms
REST, Test-driven Development (TDD), Test Automation
Other
Software Development, Back-end, WebSockets, CI/CD Pipelines, Lovable, Supabase, Generative Artificial Intelligence (GenAI), Oracle Fusion Middleware, Universal Content Management (UCM), Web App Testing, Oracle Fusion HCM, Machine Learning, Enterprise Java Beans (EJB), OpenClaw, ClaudeCode, Deno, Applied Mathematics, Large Language Models (LLMs)
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
Share your needs
Choose your talent
Start your risk-free talent trial
Top talent is in high demand.
Start hiring