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Jiayin L.

@sekai1116

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4.9
9

5.5

5.5

89%

Principal Engineer | Software & Embeded System

$40 USD / Hour

Flag of

Japan (2:04 AM)

Joined on June 20, 2025

4 Recommendations

$40 USD / Hour

Senior AI, Software, and Embedded Systems Engineer with extensive experience designing and delivering intelligent, scalable, and hardware-integrated solutions. I specialize in building high-performance software systems, distributed web platforms, cross-platform mobile applications, and embedded electronic systems. My focus is on transforming complex ideas into robust, production-ready products that combine modern software engineering, AI-driven automation, embedded firmware, and scalable system architecture. I work with startups, agencies, and enterprises to develop end-to-end solutions across SaaS platforms, AI-powered applications, IoT ecosystems, embedded devices, RF-enabled systems, and native mobile applications. My engineering methodology emphasizes clean architecture, system reliability, hardware-software integration, performance optimization, and maintainable long-term scalability. Core Expertise ✅AI & Automation OpenAI API integration, AI chat systems, machine learning solutions, Python-based automation, and intelligent workflow systems. ✅Mobile Development Flutter, FlutterFlow, React Native, Dart for building high-quality cross-platform mobile applications. ✅Frontend Engineering React.js, Next.js, Vue.js, TypeScript, JavaScript, Tailwind CSS, Bootstrap, focused on responsive and scalable UI architectures. ✅Backend Development Node.js, Express.js, Laravel, PHP, designing secure, scalable, and high-performance backend systems and APIs. ✅Embedded Systems & Firmware Engineering C/C++ development, Embedded Linux, STM32, ESP32, Arduino platforms, RTOS-based systems, IoT firmware development, sensor integration, and real-time embedded processing. ✅Electrical & Hardware Engineering Circuit design fundamentals, PCB design, hardware-software co-design, power systems integration, and communication interfaces (UART, SPI, I2C) for embedded hardware development. ✅RF & Electronics Design RF PCB layout optimization (impedance control, grounding, EMI mitigation), antenna design and tuning (Wi-Fi, BLE, LoRa, GNSS), high-speed and mixed-signal PCB design, and multilayer board optimization. Tools: ADS, CST, HFSS, Altium Designer, KiCAD, OrCAD, PADS, EasyEDA, MATLAB, NI Multisim, Proteus. ✅Databases PostgreSQL, MySQL, MongoDB, Firebase for scalable and efficient data management systems. ✅Cloud & DevOps AWS, Firebase, Vercel, DigitalOcean, Docker for deployment, scaling, and infrastructure automation. ✅APIs & Integrations REST APIs, GraphQL, Stripe, PayPal, Twilio, and third-party system integrations. I manage full project lifecycles, from initial research and system architecture through development, deployment, optimization, and long-term maintenance. My work spans AI systems, scalable SaaS platforms, embedded IoT devices, RF hardware solutions, and mobile applications, with a strong emphasis on reliability, scalability, and engineering precision.

Verifications

On time

100%

On budget

100%

Accept rate

92%

Repeat hire rate

8%

Portfolio

Portfolio

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4.9 · 9 Reviews
9 Reviews
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Dema B.

5.0

$600 USD

7 days ago

All-In-One Photobooth Software

Excellent developer and great communication throughout the project. He understood my photobooth requirements and delivered a professional solution tailored to my business needs. The software works smoothly and includes all the features we discussed. He was responsive, helpful, and kept me updated during development. I’m very satisfied with the final result and would highly recommend him to anyone looking for reliable and high-quality development work.

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Simone H.

4.6

$1,500 AUD

2 months ago

Annual Sailing Regatta Site -- 2

He is very helpful and knowledgable. We communicated daily until the project was finished. He is based in Japan which is a good timezone for me in Australia. We used a new platform can Netlify which is very user friendlly.

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Mohamed O.

5.0

£200 GBP

4 months ago

Senior AWS Developer for FinOps Platform - 12/02/2026 03:24 EST

Very professional and would work with again in the future.

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Hamad B.

5.0

$1,510 USD

5 months ago

Subscription Website

I loved to work with jiayin and do my projects on time with high quality and he have solutions for any problem to make the project in high-quality without issues and im so happy to know him and we will work together in future projects ?

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Marta R.

5.0

€500 EUR

6 months ago

Project for Jiayin L.

Jiayin is a very reliable and patient developer. He helped me migrate my Moodle platform to a new server, fixed several critical issues (DNS, access problems, course management) and always explained what he was doing in clear, simple English. Communication was fast despite the time-zone difference and he respected my security requests carefully. I’m satisfied with this collaboration and I would work with him again on similar technical projects.

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Experience

Principal Staff Engineer

Mar, 2022 - Dec, 2025

3 years, 9 months

Gree

Mar, 2022 - Dec, 2025

3 years, 9 months

-Built and shipped cross-platform mobile apps (React Native & Flutter) and responsive web apps (React/Next.js), delivering smooth UX, offline support, and fast load times. -Designed and operated REST/GraphQL backends (Node.js/NestJS + Python/FastAPI), containerized with Docker and deployed on AWS (ECS/EKS/Lambda) with GitHub Actions–based CI/CD.

Mar, 2022 - Dec, 2025

3 years, 9 months

Education

Beijing Institute of Technology

2011 - 2016

5 years

B.S. in Applied Mathematics & Computer Science

Flag of

China

2011 - 2016

5 years

Certifications

P

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