Builder

Javier Ezpeleta

Senior Fullstack Engineer · AI Systems Builder · Next.js · TypeScript · LLMs

AvailableAI-native product engineering · Fullstack systems · Polished UXMadrid, Spain$75/hr

About

Senior fullstack engineer with 15+ years building products from zero to scale. I’ve shipped platforms serving 40K daily users, email infrastructure handling 4M+ messages/hour, an Electron AI organizer used by 10K people across 10M files, and smart contracts with $6M in volume. I work end to end across Next.js, React, TypeScript, Node.js, PostgreSQL, AI/LLM integrations, agents, MCP servers, Electron and Web3. I care equally about speed and polished UX, build AI-natively, and love turning ambitious ideas into production software. Community-first builder, musician and artist based in Madrid. EU citizen, remote-first, open to relocation and looking for a team to grow with.

Skills

Next.js React TypeScript Node.jsPostgreSQLAI AgentsLLM IntegrationsMCP ServersPrompt EngineeringTailwind CSSshadcn/uiSupabaseVercelElectronFramer MotionSolidityLens SDKWeb3

Experience

Fullstack Engineer

Riyadh Air Metropolitano · Jun 2026 to Jul 2026

Built 100% of the official website for Atlético de Madrid’s stadium — Madrid’s top concert venue and host of the 2027 UEFA Champions League final. Shipped solo with Webflow and Figma, driven by Claude via MCP.

Senior Fullstack Engineer

VeryChess · Dec 2024 to May 2025

Built an interactive chess learning platform with two top-100 Grandmasters. Developed AI-powered training modules, quizzes and performance dashboards using Anthropic LLMs.

Senior Fullstack Engineer

Sparkle · every.to · Jul 2024 to Sep 2024

Built a macOS Electron app that automatically organizes files using AI classification. Reached 10K+ users and organized 10M+ files.

Founding Engineer

Flightcast · Apr 2024 to Jun 2024

Built a video-first podcasting platform from zero, including real-time analytics, an online video editor, AI-powered chapter detection and ad placement.

Co-founder & CTO

Inmagic.ai · Sep 2023 to Mar 2024

Built an AI assistant for Instagram creators from zero to launch, reaching 3K users. Integrated 50+ GPT-powered use cases across auto-replies, content generation and analytics; owned architecture, backend, frontend, LLM pipelines and deployment.

Co-founder & CTO

Nueva Technologies · Sep 2021 to Dec 2022

Led Web3 development for client projects and deployed smart contracts for five NFT collections with $6M in total volume.

Founding Engineer

MusicProdigy · Nov 2013 to Sep 2021

Led development of a music education platform serving 40,000 daily active users across web, Windows, Mac and iOS. Built custom ML libraries for polyphonic audio detection, automated grading and real-time performance feedback.

Education

Universidad Pontificia de Salamanca

B.S., Computer Science & Information Systems · Sep 2008 to Jun 2012

Bachelor’s degree completed in 2012.

Projects

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