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I am a Senior Java Developer with 10+ years of experience building scalable backend systems and cloud-native microservices across cybersecurity and fintech domains. I design high-performance Java applications on GCP and AWS, leveraging Kafka, Spring Boot, and PostgreSQL to handle large-scale data pipelines. I take ownership from architecture through production deployment, with a strong emphasis on clean code and test automation.…I am a Senior Java Developer with 10+ years of experience building scalable backend systems and cloud-native microservices across cybersecurity and fintech domains. I design high-performance Java applications on GCP and AWS, leveraging Kafka, Spring Boot, and PostgreSQL to handle large-scale data pipelines. I take ownership from architecture through production deployment, with a strong emphasis on clean code and test automation.

Sam(Haitao) Li

Back-End Developer, Full Stack Developer, Web Developer, +2

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I am a Senior Java Developer with 10+ years of experience building scalable backend systems and cloud-native microservices across cybersecurity and fintech domains. I design high-performance Java applications on GCP and AWS, leveraging Kafka, Spring Boot, and PostgreSQL to handle large-scale data pipelines. I take ownership from architecture through production deployment, with a strong emphasis on clean code and test automation.…I am a Senior Java Developer with 10+ years of experience building scalable backend systems and cloud-native microservices across cybersecurity and fintech domains. I design high-performance Java applications on GCP and AWS, leveraging Kafka, Spring Boot, and PostgreSQL to handle large-scale data pipelines. I take ownership from architecture through production deployment, with a strong emphasis on clean code and test automation.

Available to hire

I am a Senior Java Developer with 10+ years of experience building scalable backend systems and cloud-native microservices across cybersecurity and fintech domains. I design high-performance Java applications on GCP and AWS, leveraging Kafka, Spring Boot, and PostgreSQL to handle large-scale data pipelines. I take ownership from architecture through production deployment, with a strong emphasis on clean code and test automation.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Language

English

Advanced

Work Experience

Senior Software Engineer at Freelance

October 1, 2025 - Present

Developed a full-stack web application using Spring Boot and React, implementing user authentication and database integration. Built asynchronous backend with FastAPI and integrated OpenAI GPT API for conversational AI, including ReAct agent tool chain for tool calls and external API queries. Implemented Server-Sent Events (SSE) for real-time streaming with stability behind Nginx, and managed session history on PostgreSQL with SQLAlchemy, including indexing and query optimization for high concurrency. Deployed on AWS EC2 with systemd, Nginx as reverse proxy, and implemented log monitoring with retry mechanisms for API rate limits. Diagnosed production issues such as SSE disconnects and network timeouts and authored troubleshooting scripts.

Senior Software Engineer at Fortinet

January 1, 2021 - October 1, 2025

Led design and development of scalable backend features for virtual machines and multi-cloud platforms (AWS, Azure, GCP), increasing system throughput. Integrated YARA rules and custom signature engines to improve threat detection, built tools for real-time statistics reporting, and designed SNMP traps and MIB-based diagnostics. Developed CLI tools and RPC APIs, delivered backup/restore features, and upgraded critical components. Implemented RBAC, resolved memory leaks, and built CI/CD pipelines with Docker, GitLab, and Jenkins to accelerate releases by 20%.

Senior Software Engineer at Credit-IT Finance Technology (Fintech)

August 1, 2017 - January 1, 2021

Engineered a scalable P2P lending platform connecting 100K+ users and enabling over $50M in transactions. Led end-to-end architecture including matching engine, voiceprint recognition (AI/ML), call center, electronic contracts, and work order management. Optimized databases for high-volume real-time financial operations and built AI-powered voiceprint recognition to reduce fraud, along with AI-driven 24/7 customer service robots to improve response rates. Migrated and modernized cloud infrastructure with OpenStack, Docker, and Kubernetes, and implemented centralized logging with ELK for monitoring and incident response.

Senior Software Developer at Juniper Networks – Beijing

July 1, 2012 - July 1, 2017

Designed and optimized high-availability backend services for network device management, supporting 10,000+ devices globally. Improved JVM performance and cluster resilience under high concurrency, led RESTful API development and microservices deployment, and contributed to the Space Platform (NSM) and Firewall frontend/backend. Enhanced device discovery, configuration management, inventory, and automation scripts, and delivered cloud-based CSP frontend/configuration for seamless device integration.

Senior Software Engineer at Credit-IT Finance Technology

August 1, 2017 - January 1, 2021

Engineered and launched a scalable P2P lending platform, connecting 100K+ users and facilitating over $50M in transactions. Led architecture and development for end-to-end systems including matching engine, voiceprint recognition (big data/AI), call center, electronic contracts, and work order management. Designed and optimized databases to support high-volume, real-time financial operations. Built AI-powered voiceprint recognition and knowledge maps, reducing fraud by 20% and enabling detailed customer risk analysis. Developed 24/7 AI-driven customer service robots using machine learning, improving response rates and customer satisfaction. Architected cloud infrastructure using OpenStack, Docker, and Kubernetes, increasing deployment efficiency by 35%. Implemented ELK stack for centralized log management and analytics, enhancing system monitoring and incident response.