Freelancer profile translated to English.
Back to original languageAbout Sergio
Senior PHP / Symfony / Laravel (Backend) Developer · React Native (Frontend) · AI & Claude Code Specialist · CTO
PHP · Symfony · Laravel · React · React Native · Next.js · TypeScript · AWS · Docker · AI · Claude Code
Hello! I'm Sergio, a senior backend developer and CTO with a strategic and product-oriented mindset. In over 15 years, I've designed robust REST APIs, scalable web platforms, and high-performance backend systems for startups and scale-ups, using Symfony and Laravel under SOLID, DDD, and clean architecture principles.
As CTO and technical leader, I've managed multidisciplinary and distributed teams, defined technical roadmaps, set engineering standards, and ensured the reliable delivery of complex products.
Frontend and Mobile: I also build modern web interfaces with React, Next.js, TypeScript, and TailwindCSS, and iOS and Android mobile apps with React Native — a single technical partner covering API, web, and mobile from a single source of truth.
I work fluidly with Claude Code to prototype faster and deliver better code and UI, without sacrificing review or architectural rigor. AI is part of how I work, not a substitute for engineering judgment.
How I work: I focus on specific, well-defined tasks (architecture audits, API design, backend modules, web or mobile features, technical leadership, AI prototyping) where I provide clear and rapid value.
What my clients value:
- Complex ideas turned into clear, functional solutions.
- Code quality, performance, and long-term maintainability.
- A real technical partner who helps make the right technology decisions.
Areas: technical leadership and architecture · REST APIs with Symfony and Laravel · microservices and legacy modernization · React, Next.js, TypeScript, Tailwind · iOS/Android with React Native · MySQL, Postgres, Aurora · AWS, Docker, CI/CD, and DevOps.
Let's connect! (EN: senior backend developer & CTO — happy to work in English too.)
Spanish
Native or bilingual
English
Native or bilingual
Catalan
Fluent
Remote only
Primarily works remotely
Experience
- FreelancerFreelancerTELECOMMUNICATIONSJanuary 2020 - Today (6 years and 7 months)Barcelona, SpainExperienced technology leader with an extensive background and passion for helping organizations achieve success.
- Bake250ºCTOTELECOMMUNICATIONSSeptember 2018 - Today (7 years and 11 months)Barcelona, SpainMy main goal was to optimize processes to improve team performance, reduce wasteful processes and improvement of agile practices.• Constantly improving the architecture, migrating existing code to new micro services• Responsibility for all technical decisions• Worked with the CEOs and the product management to develop the business plan and long-term tech strategy & vision• Development of a REST API using Symfony• Development of a mobile applications using React Native• Development of a websites using React
- SignaturitSenior Backend DeveloperTELECOMMUNICATIONSSeptember 2017 - August 2018 (11 months)Barcelona, SpainI worked on the core backend team with an amazing team.• Working on additional features to improve the user experience• Development of a REST API using Symfony• Constantly improving the architecture, migrating existing code to new micro services• Working with the customer support team to help them with the tickets: bugs, doubts, integration problems.
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Education
- Higher Technician in Computer Application Development (DAI)IES Azarquiel2011Técnico Superior en Desarrollo de Aplicaciones Informáticas (DAI)
- Higher Technician in Computer Systems Administration (ASI)IES Azarquiel2009Técnico Superior en Administración de Sistemas Informáticos (ASI)
Certifications
- Android Application DeveloperUniversidad Camilo Jose Cela2012
- Cisco CCNNA Exploration 4.0 (Cisco Certified Network Associate)Cisco Networking Academy2010