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I’m a senior full-stack product engineer with 7+ years of experience building production web applications and SaaS products end-to-end, from translating founder and business needs into technical architecture through shipping, testing, deployment, and ongoing production support. I’ve built AI-powered product experiences with a strong focus on usability, reliability, and pragmatic delivery in small, founder-led teams. My day-to-day strength is owning the full lifecycle: designing frontend systems with Next.js/React/TypeScript, building backend APIs with FastAPI and Python (plus Node.js when needed), modeling data in PostgreSQL, and integrating authentication, billing, and real-time features. I also bring a reliability mindset—automation with Playwright/Cypress, CI/CD via GitHub Actions, and production monitoring using Sentry—along with accessibility awareness (WCAG) so the end product is both high-quality and usable.…I’m a senior full-stack product engineer with 7+ years of experience building production web applications and SaaS products end-to-end, from translating founder and business needs into technical architecture through shipping, testing, deployment, and ongoing production support. I’ve built AI-powered product experiences with a strong focus on usability, reliability, and pragmatic delivery in small, founder-led teams. My day-to-day strength is owning the full lifecycle: designing frontend systems with Next.js/React/TypeScript, building backend APIs with FastAPI and Python (plus Node.js when needed), modeling data in PostgreSQL, and integrating authentication, billing, and real-time features. I also bring a reliability mindset—automation with Playwright/Cypress, CI/CD via GitHub Actions, and production monitoring using Sentry—along with accessibility awareness (WCAG) so the end product is both high-quality and usable.

Adonis Xiao

Full Stack Developer, Web Developer, Back-End Developer, +4

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I’m a senior full-stack product engineer with 7+ years of experience building production web applications and SaaS products end-to-end, from translating founder and business needs into technical architecture through shipping, testing, deployment, and ongoing production support. I’ve built AI-powered product experiences with a strong focus on usability, reliability, and pragmatic delivery in small, founder-led teams. My day-to-day strength is owning the full lifecycle: designing frontend systems with Next.js/React/TypeScript, building backend APIs with FastAPI and Python (plus Node.js when needed), modeling data in PostgreSQL, and integrating authentication, billing, and real-time features. I also bring a reliability mindset—automation with Playwright/Cypress, CI/CD via GitHub Actions, and production monitoring using Sentry—along with accessibility awareness (WCAG) so the end product is both high-quality and usable.…I’m a senior full-stack product engineer with 7+ years of experience building production web applications and SaaS products end-to-end, from translating founder and business needs into technical architecture through shipping, testing, deployment, and ongoing production support. I’ve built AI-powered product experiences with a strong focus on usability, reliability, and pragmatic delivery in small, founder-led teams. My day-to-day strength is owning the full lifecycle: designing frontend systems with Next.js/React/TypeScript, building backend APIs with FastAPI and Python (plus Node.js when needed), modeling data in PostgreSQL, and integrating authentication, billing, and real-time features. I also bring a reliability mindset—automation with Playwright/Cypress, CI/CD via GitHub Actions, and production monitoring using Sentry—along with accessibility awareness (WCAG) so the end product is both high-quality and usable.

Available to hire

I’m a senior full-stack product engineer with 7+ years of experience building production web applications and SaaS products end-to-end, from translating founder and business needs into technical architecture through shipping, testing, deployment, and ongoing production support. I’ve built AI-powered product experiences with a strong focus on usability, reliability, and pragmatic delivery in small, founder-led teams.

My day-to-day strength is owning the full lifecycle: designing frontend systems with Next.js/React/TypeScript, building backend APIs with FastAPI and Python (plus Node.js when needed), modeling data in PostgreSQL, and integrating authentication, billing, and real-time features. I also bring a reliability mindset—automation with Playwright/Cypress, CI/CD via GitHub Actions, and production monitoring using Sentry—along with accessibility awareness (WCAG) so the end product is both high-quality and usable.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Language

English

Advanced

Greek, Modern

Advanced

Chinese

Intermediate

Work Experience

Senior Full-Stack Product Engineer at Exeltiq (Exeltive)

September 1, 2025 - June 1, 2026

Built Exeltiq, a production CRM SaaS platform, as the primary full-stack developer in a small team working directly with founders. Owned architecture and implementation across frontend, backend, authentication, data modeling, and deployment. Implemented APIs with FastAPI and PostgreSQL schemas for core SaaS operations, and integrated Clerk for authentication and user management. Delivered a component-driven React frontend with attention to performance and maintainability, and applied WCAG accessibility standards across key UI components. Implemented Playwright/Cypress test suites and set up GitHub Actions CI/CD to run tests on every pull request. Added Sentry-based telemetry and used it to investigate and fix production incidents, improving reliability and iterating on UX with founder and early-user feedback.

Full-Stack Developer at Exeltiq (Exeltive)

September 1, 2025 - June 30, 2026

Built Exeltiq, a production multi-tenant CRM for gyms, clinics, and sports clubs in Cyprus. Designed multi-tenant architecture and implemented Clerk JWT authentication for business owners and members. Implemented Stripe billing for subscriptions and productized add-ons such as SMS credits, booking packages, and shop checkout. Built an appointment booking flow where members buy packages and redeem them for fitness, physio, and grooming services. Developed an SMS credit wallet (Stripe to credits to Twilio) and automated SMS/email campaigns. Implemented a referral program with discounted first-month subscriptions and non-refundable platform credits.

AI Application Developer at Corva.ai

March 1, 2025 - July 1, 2025

Integrated AI capabilities into user-facing product experiences, focusing on practical usability, reliability, and business value. Explored AI-driven automation patterns to improve user productivity within existing product surfaces, and applied full-stack engineering skills to ship AI-powered features with appropriate human verification for correctness and security.

Backend Developer (Contract) at Corva.ai

March 1, 2025 - July 31, 2025

Joined after a company hackathon and completed backend work on a real-time oil and gas data platform. Developed backend services supporting high-volume operational data for live visual dashboards. Implemented WebSockets and asynchronous job-status flows so the frontend could accurately reflect backend job stages and progress.

Senior Full-Stack Engineer at Emerton

January 1, 2023 - January 1, 2025

Designed and delivered production-ready web applications for startup and business clients, working independently from requirements through delivery. Built scalable frontend systems using React, Next.js, and TypeScript with reusable components shared across projects. Developed backend APIs and services using Node.js and Express (with Python integration), connected to PostgreSQL and MongoDB, and implemented authentication/authorization and payment integrations (Stripe). Worked directly with clients to scope requirements, propose solutions, and communicate trade-offs and risks.

Senior Full-Stack Engineer (Contract) at Emerton

January 1, 2023 - February 28, 2025

Delivered production web applications for about 7 business and startup clients. Built React/Next.js/TypeScript frontends and FastAPI/Node.js APIs. Implemented authentication, payments, and third-party API integrations. Owned scoping, delivery, and production fixes independently.

Backend Developer at ACLIT

January 1, 2021 - January 1, 2022

Developed scalable backend systems using Node.js, Express, Laravel, and MySQL/PostgreSQL/MongoDB. Designed RESTful API architectures for web and mobile applications. Implemented secure authentication using JWT and OAuth, and documented APIs with Swagger/Postman. Improved reliability and performance through testing, debugging, and query optimization.

Backend Developer (Contract) at ACLIT

January 1, 2021 - December 31, 2022

Developed REST APIs using Node.js/Express and Python for web and mobile clients. Implemented JWT/OAuth authentication and optimized PostgreSQL, MySQL, and MongoDB queries. Documented APIs with Swagger and Postman.

Frontend Engineer at GMO Internet Group, Inc.

January 1, 2020 - January 1, 2021

Built React and TypeScript interfaces and reusable UI components. Supported production frontend maintenance, debugging, and performance improvements.

Junior MERN Stack Developer at TechWave Solutions

January 1, 2018 - January 1, 2020

Built full-stack features with React, Node.js, Express, and MongoDB. Deployed applications using AWS EC2, PM2, and Nginx.