Kye Chan, Developer in Toronto, ON, Canada
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Kye Chan

Verified Expert  in Engineering

Software Developer

Toronto, ON, Canada
Toptal Member Since
July 26, 2021

Kye is a product-focused Java back-end engineer and test enthusiast with experience in the payments and banking industry, working on mission-critical systems. At Goldman Sachs, he designed and built Kafka-based event-driven microservices to decouple lengthy business workflows, reducing onboarding time from months to 10 minutes. He produces production-ready solutions that are functional, testable, observable, maintainable, extendable, and scalable.


Java, MongoDB, Amazon Web Services (AWS), Spring, SQL, Spring Boot...
Camunda BPM, Spring Boot, Java, Amazon DynamoDB, Kubernetes, Docker
Goldman Sachs
Java, MongoDB, Apache Kafka, Cucumber, REST Assured, Java 11, Microservices...




Preferred Environment

IntelliJ IDEA, GitLab, Git, Windows

The most amazing...

...tool I've worked on is an eCommerce payment system that runs 24/7 and transacted half a million GBP sales during Black Friday in 2018.

Work Experience

Java Developer (via Toptal)

2021 - 2023
  • Developed and integrated over-the-air upgrade IoT solution for 20,000+ on-field reader devices, enabling seamless fleet-wise instant or scheduled firmware updates.
  • Implemented migration of legacy connection status solution to AWS IoT lifecycle events, resulting in an 8% improvement in connection status accuracy.
  • Implemented Dwolla integration to support standard ACH deposit and rent payments. This includes funding source imbalance handling (ACH returns), destination account management, and asynchronous notifications.
  • Designed and implemented 3rd-party lease and ledger data pipeline integration to support externalizing the rent payment service.
  • Designed and implemented Stripe Checkout and multiparty payments integration to support property facility booking service.
  • Implemented small front-end updates on the management and resident portal using Angular and React to provide a better rent payment user experience.
  • Oversaw the requirement refinement, design, implementation, and testing during SDLC, working closely with corresponding parties, including the product manager, back-end/firmware development team, security team, and QA.
Technologies: Java, MongoDB, Amazon Web Services (AWS), Spring, SQL, Spring Boot, Spring Data JPA, Liquibase, PostgreSQL, Amazon Simple Queue Service (SQS), Amazon Elastic Container Service (Amazon ECS), Datadog, Terraform, Angular, gRPC, Distributed Systems, HTML, CSS, Gradle, REST APIs, HTTP REST, JUnit

Senior and Team Lead Developer

2022 - 2022
  • Transferred proprietary domain knowledge from the offshore Ruby on Rails development team to the product owner via Camunda BPMN.
  • Coached the architect and Ruby on Rails developers on the Camunda 8 workflow development, such as Java, BPMN, and other Camunda 8 cloud services.
  • Coached a DevOps engineer on Java development pipelines such as the Maven build and deploy pipeline and Dockerizing and parameterizing a Spring Boot application.
  • Established the Camunda 8 spring-zeebe integration project base, including testing utility, capability, and workflow deployment.
  • Designed and built the project funding slotting workflow and loan cost calculation workflow via Java and Camunda 8.
  • Inspected and discovered major correctness and maintainability issues in Spring Boot web API for the unsecured loans product line.
Technologies: Camunda BPM, Spring Boot, Java, Amazon DynamoDB, Kubernetes, Docker

Associate (Software Engineer - Transaction Banking)

2019 - 2021
Goldman Sachs
  • Built a solution to support API and UI-driven onboarding processes to Stripe Treasury (Banking as a Service or BaaS).
  • Designed and built Kafka-based event-driven microservices to decouple lengthy business workflows, which reduced onboarding time from months to ten minutes.
  • Designed and built the Camunda maker-checker workflow library and standardized the process.
  • Designed and built the Camunda workflow library handling and monitoring asynchronous acknowledgments.
  • Established a behavioral testing practice and regression tool to reduce manual testing effort.
  • Researched the feasibility of a MongoDB client-side field-level encryption with Spring-data-MongoDB integration.
Technologies: Java, MongoDB, Apache Kafka, Cucumber, REST Assured, Java 11, Microservices, Amazon Elastic Container Service (Amazon ECS), Camunda BPM, REST APIs, Message Queues, Terraform, JUnit, Apache Maven, GitLab, Digital Banking, Scrum, Spring, Spring Boot, Databases, NoSQL, Amazon Web Services (AWS), HashiCorp, CI/CD Pipelines, API Development

Software Engineer (Payments Platform)

2017 - 2019
  • Designed and built API to convert custom rule expressions to trigger fraud measures (3DS, CV2) for card payment.
  • Assisted new card provider and payment 3DS 1.0 integration to enable direct card payment for specific sites to reduce around 2% of the transaction cost and reduce chargebacks.
  • Migrated ApplePay payment to another provider to be in line with the provider migration.
  • Broke down and rewrote parts of a monolith toward microservices architecture to support future scaling and SaaS.
  • Maintained internal payments tool UI (payment method configuration and auditing) with AngularJS and Thymeleaf.
Technologies: Java 8, ActiveMQ, SQL, Apache Camel, Test-driven Development (TDD), WireMock, Selenium, Apache Maven, Git, Jenkins, Grafana, Nagios, Kibana, Kanban, Card Payments, Payment APIs, SQL Server 2012, Spring, AngularJS, Thymeleaf, Spring Boot, Credit Cards & Transaction Processing, Databases, Selenium API

Research Assistant Intern

2016 - 2016
Cardiff University
  • Experimented and integrated onset detection libraries.
  • Experimented with Tempo estimation in the frequency domain with Constants Q Transformation (CQT) and Tempogram Toolbox.
  • Experimented with Tempo estimation in the time domain with onset detection.
Technologies: MATLAB

Latch R2 OTA Feature & Back-end Improvements
This project implemented an AWS IoT solution for 20,000+ on-field reader devices, enabling seamless over-the-air firmware updates for fleet-wide efficiency and reliability. It also enhanced monitoring and reporting by integrating AWS IoT lifecycle events, improving connection status accuracy, and integrating Memfault reporting logic for increased visibility on debug chunks.

Additionally, back-end services were migrated from a legacy in-house framework to a modern spring-boot framework, enhancing observability and maintainability.

I operated with a high degree of autonomy while collaborating with a product manager, a staff engineer, and a QA engineer. Together, we iterated on both functional and non-functional requirements and conducted biweekly demos to showcase my progress.

Transaction Banking (Client Management)
This is a digital-first corporate banking-as-a-service (BaaS) platform built from scratch. I built solutions that revolutionized the onboarding and account opening experience, which shortened these processes' time to minutes from the industry standard of months. This was achieved by supporting external clients (partners) and internal operations to perform self-service driven by API and UI.

Payment Services
The project aims to integrate Dwolla and Stripe payment processors to support, send and receive deposit and rent payments and multiparty payments via Express Checkout, respectively. This also includes accounts onboarding, management, and different payment scenarios. These functionalities empower user experience in building services and management.

I oversaw requirement refinement, design, implementation, and testing during SDLC and worked closely with corresponding parties, including the product manager, development team, security team, and QA.

Loan Eligibility Checking & Slotting Process via Camunda 8
A loan eligibility checking/slotting process orchestrated by Camunda 8 in the back end. I led the back-end development team in Springboot and Camunda and mentored and guided offshore dev resources from different vendors to extract core proprietary orchestration logic.

Payments Platofrm (eCommerce)
As part of the payments team, I was responsible for payment methods and providers' integrations such as card, Apple Pay, Alipay, WeChat Pay, and Google Pay. Apart from an integration perspective, achieving high availability, fault-tolerance, scalability, and providing observability to both the business and team were also my main deliverables.
2015 - 2017

Bachelor's Degree in Computer Science

Cardiff University - United Kingdom

MARCH 2024 - MARCH 2027

AWS Certified DevOps Engineer – Professional

Amazon Web Services


REST APIs, API Development, Selenium API, React, Liquibase


Apache Maven, GitLab, Git, IntelliJ IDEA, Cucumber, REST Assured, Amazon Elastic Container Service (Amazon ECS), Camunda BPM, ActiveMQ, Terraform, WireMock, Jenkins, Grafana, Nagios, Kibana, Karate API Testing, MATLAB, HashiCorp, Amazon Simple Queue Service (SQS), Gradle


JUnit, Spring, Spring Boot, Selenium, Apache Camel, Redux, AngularJS, Thymeleaf, Angular, gRPC


Java, Java 11, Java 8, SQL, Python, JavaScript, TypeScript, HTML, CSS


Microservices, Test-driven Development (TDD), Testing, Object-oriented Programming (OOP), Kanban, Scrum, DevOps


Databases, MongoDB, NoSQL, SQL Server 2012, Spring Data JPA, PostgreSQL, Datadog, Amazon DynamoDB


Apache Kafka, Windows, Amazon Web Services (AWS), Kubernetes, Docker, AWS IoT Core


Message Queues, Payment APIs, Digital Banking, Software Development, Card Payments, Credit Cards & Transaction Processing, Data Analysis, Image Processing, Networks, CI/CD Pipelines, Zeebe, Distributed Systems, Cloud, Back-end, Back-end Development, HTTP REST

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