Sergio Pérez

Backend.Frontend.AI-first.

Freelance Senior Developer & Tech Lead.
Today with React

I turn ideas into products that hold up in production: the API in Symfony or Node, the app in React or React Native, the cloud on AWS. AI agents speed up the work.

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Services

What I bring to your team.

Frontend

Web & mobile

Interfaces people enjoy using.

Web apps in React and Next.js, mobile apps in React Native and Flutter. Fast, accessible, and easy for the next developer to pick up.

Core: ReactNext.jsTypeScriptTailwindSCSSReact NativeExpoFlutter

Backend

Logic & data

APIs built to last.

REST APIs in Symfony, Laravel and Node, shaped with DDD and CQRS and backed by PHPUnit tests. Data in PostgreSQL or MySQL, and legacy monoliths split into microservices.

Core: PHPSymfonyLaravelDoctrineNode.jsPostgreSQLMySQL

DevOps

Infrastructure

Infrastructure that runs itself.

Containerised apps, automated CI/CD pipelines and cloud infrastructure on AWS, Google Cloud or DigitalOcean, from the first deploy to a stable production.

Core: DockerAWSECS/FargateGoogle CloudDigitalOceanBitbucket CI

AI & Agents

How I work

AI is part of how I build.

Coding agents plan, write and review alongside me, so I move faster without lowering the bar.

Core: Claude CodeCursorLLM APIsPrompt engineering

Experience

What I've done.

Startups
Led the tech side of startups, owning every technical decision as the team grew.
Scale
Built and maintained complex web and mobile apps for large online companies.
Architecture
Refactored legacy platforms into modern, maintainable code and migrated existing systems to microservices on AWS.

Contact

Let's talk.

Hiring, building something, or stuck on a hard technical problem?
Write to me.

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