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I’m Samuel Liu, a Senior Full Stack Engineer with 9 years of experience building scalable, high-performance backend systems and AI-powered features. I’m proficient in JavaScript, TypeScript, Java, and Kotlin, with a strong focus on API design, server performance optimization, and cloud-based microservices architectures. I also embrace DevOps practices, CI/CD, and containerization using AWS, Docker, and Kubernetes to deliver reliable, scalable software. I’m adept at working with SQL (PostgreSQL, MySQL) and NoSQL (MongoDB, DynamoDB), and I enjoy collaborating with cross-functional teams to turn ideas into robust solutions. I take pride in clean, maintainable code and solving complex technical challenges in fast-paced environments, while mentoring teammates and continuously learning.…I’m Samuel Liu, a Senior Full Stack Engineer with 9 years of experience building scalable, high-performance backend systems and AI-powered features. I’m proficient in JavaScript, TypeScript, Java, and Kotlin, with a strong focus on API design, server performance optimization, and cloud-based microservices architectures. I also embrace DevOps practices, CI/CD, and containerization using AWS, Docker, and Kubernetes to deliver reliable, scalable software. I’m adept at working with SQL (PostgreSQL, MySQL) and NoSQL (MongoDB, DynamoDB), and I enjoy collaborating with cross-functional teams to turn ideas into robust solutions. I take pride in clean, maintainable code and solving complex technical challenges in fast-paced environments, while mentoring teammates and continuously learning.

Samuel Liu

Full Stack Developer, Back-End Developer, Web Developer, +5

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I’m Samuel Liu, a Senior Full Stack Engineer with 9 years of experience building scalable, high-performance backend systems and AI-powered features. I’m proficient in JavaScript, TypeScript, Java, and Kotlin, with a strong focus on API design, server performance optimization, and cloud-based microservices architectures. I also embrace DevOps practices, CI/CD, and containerization using AWS, Docker, and Kubernetes to deliver reliable, scalable software. I’m adept at working with SQL (PostgreSQL, MySQL) and NoSQL (MongoDB, DynamoDB), and I enjoy collaborating with cross-functional teams to turn ideas into robust solutions. I take pride in clean, maintainable code and solving complex technical challenges in fast-paced environments, while mentoring teammates and continuously learning.…I’m Samuel Liu, a Senior Full Stack Engineer with 9 years of experience building scalable, high-performance backend systems and AI-powered features. I’m proficient in JavaScript, TypeScript, Java, and Kotlin, with a strong focus on API design, server performance optimization, and cloud-based microservices architectures. I also embrace DevOps practices, CI/CD, and containerization using AWS, Docker, and Kubernetes to deliver reliable, scalable software. I’m adept at working with SQL (PostgreSQL, MySQL) and NoSQL (MongoDB, DynamoDB), and I enjoy collaborating with cross-functional teams to turn ideas into robust solutions. I take pride in clean, maintainable code and solving complex technical challenges in fast-paced environments, while mentoring teammates and continuously learning.

Available to hire

I’m Samuel Liu, a Senior Full Stack Engineer with 9 years of experience building scalable, high-performance backend systems and AI-powered features. I’m proficient in JavaScript, TypeScript, Java, and Kotlin, with a strong focus on API design, server performance optimization, and cloud-based microservices architectures. I also embrace DevOps practices, CI/CD, and containerization using AWS, Docker, and Kubernetes to deliver reliable, scalable software.

I’m adept at working with SQL (PostgreSQL, MySQL) and NoSQL (MongoDB, DynamoDB), and I enjoy collaborating with cross-functional teams to turn ideas into robust solutions. I take pride in clean, maintainable code and solving complex technical challenges in fast-paced environments, while mentoring teammates and continuously learning.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

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Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Intermediate

Intermediate

Language

Javanese

Advanced

English

Fluent

Work Experience

Senior Full Stack Engineer at Optum

November 1, 2022 - Present

Developed and deployed an AI-powered claims adjudication system that cut out-of-network processing time from about 15 minutes to under 3 minutes, improving operational efficiency by around 80%. Engineered NLP and rules-based pipelines to automate claims validation, eligibility verification, and payment determination. Built predictive models using Python, TensorFlow/PyTorch, and scikit-learn to identify anomalies and speed adjudication decisions. Designed scalable data pipelines on AWS/Azure to process high-volume claims in real-time, supporting millions of transactions monthly. Collaborated with cross-functional teams to integrate AI models into existing claims management platforms, reducing manual intervention and costs. Implemented OCR/document extraction to accelerate intake of unstructured claim documents and designed a hybrid retrieval vector + keyword system for payer policy search.

Senior Software Engineer at Sutter Health

April 1, 2021 - September 1, 2022

Implemented doctor-patient chat feature in Android app (Kotlin), leveraging WebSocket connections for real-time messaging; added read receipts and push notifications to boost engagement; integrated WebRTC-based video and audio calls with built-in end-to-end encryption (DTLS/SRTP) to accommodate user needs and bandwidth constraints.

Software Engineer at Sutter Health

May 1, 2018 - March 1, 2021

Designed and implemented RESTful API endpoints in Java to support messaging and telehealth features; enhanced telehealth with WebRTC-based video and audio communication; refactored legacy REST endpoints into GraphQL queries and mutations to improve data retrieval and mobile support; collaborated with frontend and mobile teams to define GraphQL queries and fragments; containerized services with Docker and Kubernetes, enabling CI/CD with GitHub Actions; ensured HIPAA-compliant data handling and secure pipelines; mentored junior engineers.

Software Engineer at Amazon

June 1, 2013 - April 1, 2018

Implemented scalable backend microservices in Java (Spring Boot) and AWS Lambda powering Prime Video home feed, search results, and Continue Watching modules; optimized video encoding workflows by integrating FFmpeg, AWS Elastic Transcoder, and later MediaConvert, reducing encoding times by 30% while preserving adaptive bitrate quality. Implemented content delivery optimizations with AWS CloudFront and Route 53, and custom caching to reduce latency. Contributed to Prime Video web frontend by developing React components for Home, Details, and Playback pages, ensuring cross-platform consistency. Collaborated with UX and design teams to implement WCAG accessibility and internationalization for subtitles and localization.

Software Development Engineer Intern at Amazon

May 1, 2012 - August 1, 2012

Refactored a legacy internal module, improving performance and reducing average response times by 40%; built RESTful APIs for an internal platform to enable data exchange between microservices and downstream analytics systems; integrated monitoring and logging with AWS CloudWatch to improve production visibility.

Software Development Engineer at Amazon

June 1, 2013 - April 1, 2018

Implemented scalable backend microservices in Java (Spring Boot) and AWS Lambda powering Prime Video home feed, search results, and Continue Watching modules, serving millions of daily active users globally. Optimized video encoding workflows by integrating FFmpeg, AWS Elastic Transcoder, and later MediaConvert, reducing encoding times by 30% while maintaining adaptive bitrate quality. Implemented content delivery optimizations with AWS CloudFront, Route 53, and custom caching strategies. Contributed to the Prime Video web frontend by developing React components for Home, Details, and Playback pages, ensuring accessible and cross-platform rendering. Worked with UX/design teams to implement accessibility (WCAG 2.0) and internationalization (i18n) features for subtitles and localization.