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I'm a freelance Full Stack Engineer and Cloud Developer based in Madrid, Spain, with over 4 years of production experience building reliable web apps and scalable backend systems. I specialize in the JavaScript ecosystem (React, Node.js) with practical AWS cloud integration and automation.\n\nCurrently operating as an independent engineer, I thrive in autonomous roles, solving complex technical problems and delivering polished products. I'm available for remote or hybrid roles and both B2B contracting and standard employment. Check my portfolio at ewejose.com.…I'm a freelance Full Stack Engineer and Cloud Developer based in Madrid, Spain, with over 4 years of production experience building reliable web apps and scalable backend systems. I specialize in the JavaScript ecosystem (React, Node.js) with practical AWS cloud integration and automation.\n\nCurrently operating as an independent engineer, I thrive in autonomous roles, solving complex technical problems and delivering polished products. I'm available for remote or hybrid roles and both B2B contracting and standard employment. Check my portfolio at ewejose.com.

Jose Omusi Saez

Full Stack Developer, Game Developer, Web Developer, +3

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I'm a freelance Full Stack Engineer and Cloud Developer based in Madrid, Spain, with over 4 years of production experience building reliable web apps and scalable backend systems. I specialize in the JavaScript ecosystem (React, Node.js) with practical AWS cloud integration and automation.\n\nCurrently operating as an independent engineer, I thrive in autonomous roles, solving complex technical problems and delivering polished products. I'm available for remote or hybrid roles and both B2B contracting and standard employment. Check my portfolio at ewejose.com.…I'm a freelance Full Stack Engineer and Cloud Developer based in Madrid, Spain, with over 4 years of production experience building reliable web apps and scalable backend systems. I specialize in the JavaScript ecosystem (React, Node.js) with practical AWS cloud integration and automation.\n\nCurrently operating as an independent engineer, I thrive in autonomous roles, solving complex technical problems and delivering polished products. I'm available for remote or hybrid roles and both B2B contracting and standard employment. Check my portfolio at ewejose.com.

Available to hire

I’m a freelance Full Stack Engineer and Cloud Developer based in Madrid, Spain, with over 4 years of production experience building reliable web apps and scalable backend systems. I specialize in the JavaScript ecosystem (React, Node.js) with practical AWS cloud integration and automation.\n\nCurrently operating as an independent engineer, I thrive in autonomous roles, solving complex technical problems and delivering polished products. I’m available for remote or hybrid roles and both B2B contracting and standard employment. Check my portfolio at ewejose.com.

Skills

Experience Level

Expert

Expert

Expert

Expert

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Expert

Expert

Expert

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Expert

Expert

Expert

Expert

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Expert

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Expert

Intermediate

Intermediate

Intermediate

Language

Spanish; Castilian

Fluent

English

Advanced

Work Experience

Game Developer at Xenova Rush

January 1, 2020 - Present

Currently developing Xenova Rush, a competitive multiplayer game featuring fast-paced melee combat and advanced parkour movement. I designed and programmed every aspect of the game: client prediction, server reconciliation, authoritative physics, and automatic server scaling in AWS. The project demonstrates my ability to design distributed systems, optimize real-time networking, and deliver a complete product across backend, frontend, and game architecture. Tools include Git/GitHub, Docker, CI/CD (Jenkins, Vercel), Unity, Prisma, PostHog, and more.

Software Engineer at Siemens

December 31, 2024 - September 8, 2025

I worked adding and supporting features to the backend and frontend for rail automation systems, with focus on passenger safety and adherence to strict guidelines. Technologies used included Java, TypeScript, Angular, Node.js, MongoDB, Jenkins, and Doors.

Independent Projects / Freelance Developer at Self-Employed

December 31, 2023 - September 8, 2025

Over the years, I built a torrent system, web apps with custom servers running in the cloud, small Android applications, and automation/scraping tools for the web along data analysis.

Independent Lead Full Stack Engineer at Independent Engineer (Autónomo)

January 1, 2020 - November 25, 2025

Architecting and deploying complex software products across the full engineering lifecycle: system design, frontend implementation, cloud infrastructure, and release management. Building production web applications and serverless backends; strong focus on React, Node.js, TypeScript, Python, and cloud automation. Operate autonomously solving complex technical problems and delivering polished products. Open to remote or hybrid roles; available for B2B contracting or standard employment.

Software Engineer at Siemens

December 31, 2024 - December 31, 2024

Contributed to backend and frontend of safety-critical rail automation systems within an Enterprise Agile environment. Designed hybrid cloud infrastructure (AWS & Serverless) with Lambda and API Gateway; implemented Cognito for authentication, DynamoDB for high-performance data access, and Terraform for infrastructure as code. Worked on game-engine integration (Unity & C#) and network optimizations (Client-Side Prediction, Server Reconciliation, Lag Compensation). Built CI/CD pipelines using GitHub Actions to deploy Next.js web platforms to Vercel and serverless functions to AWS. Led product strategy and managed a distributed team to deliver Xenova Rush and other client solutions, including multi-tenant booking and e-commerce platforms.

Independent Lead Full Stack Engineer at Self-employed / Independent Contractor

January 1, 2020 - November 25, 2025

Architected and deployed complex software products end-to-end, owning the full engineering lifecycle from system design and frontend development to cloud infrastructure, release management, and ongoing maintenance. Experienced in delivering polished products as a remote, autonomous engineer.

Software Engineer at Siemens

January 1, 2024 - January 1, 2024

Backend and frontend development for safety-critical rail automation within an Enterprise Agile environment. Designed a hybrid cloud architecture on AWS (Serverless, API Gateway, Cognito, DynamoDB) and implemented scalable game-server components with AWS GameLift. Built a serverless backend for non-real-time logic, plus Unity-based game client/server with high-frequency networking (Client-Side Prediction, Server Reconciliation, Lag Compensation). Implemented CI/CD pipelines (GitHub Actions) and IaC with Terraform; managed authentication and data services; led product strategy and coordinated a remote team of freelancers for Xenova Rush, a high-performance multiplayer project. Drove additional client solutions including a multi-tenant Booking SaaS platform (Next.js 15, Supabase, Prisma) and OtakuCollector Shopify store.

Independent Lead Full Stack Engineer at Self-employed (Autónomo)

January 1, 2020 - November 25, 2025

Architecting and deploying complex software products across frontend, backend and cloud. Owns the full engineering lifecycle, from system design and frontend implementation to cloud infrastructure and release management. Proficient in React, Node.js, AWS, and automation for scalable deployments.

Software Developer / Consultant at Client Solutions, SaaS & Web Development

January 1, 2020 - November 25, 2025

Delivered custom full-stack web solutions for diverse business clients, including multi-tenant booking platforms, e-commerce tooling, dashboards, and automated testing/deploy pipelines. Led implementations using Next.js, Supabase, Prisma, and modern testing stacks.