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Iván Rodríguez Calleja

Senior Frontend Engineer | React, TypeScript & Product-Focused UI/UX
Residence:
Spain
City:
Barcelona
Age:
29
0%
Spanish
0%
English (B2)
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Experience

  • Agentero — Frontend Lead & Architect
    Front-End Developer
    Apr 2019 - present
    • Modernized a legacy Rails–React application into a scalable React/Next.js architecture, leveraging React Server Components and SSR. This migration improved performance, developer velocity, and end-user experience.
    • Architected and scaled a modular design system, leading the migration from PandaCSS to TailwindCSS, ensuring styling consistency, maintainability, and adoption across multiple micro-frontends.
    • Drove experimentation and iteration by building frontend foundations that supported rapid A/B testing and data-driven product decisions, enabling faster validation of growth opportunities.
    • Partnered with designers, PMs, and engineers to ship accessible, polished, and conversion-focused interfaces, reducing friction in key user flows.
    • Championed modern React features (React 19 concurrent rendering, Context API, React Testing Library), improving application performance and test coverage by 20%.
    • Mentored engineers and led code reviews, fostering knowledge sharing, transparency, and a high-quality engineering culture.
  • Plain Concepts — Full Stack Developer
    Full Stack Developer
    Apr 2016 - Apr 2019
    • Built and maintained server-side applications with .NET Core, C#, and SQL Server, developing strong foundations in testing, architecture (DDD), and performance optimization.
    • Gained hands-on experience with Azure-based deployments, CI/CD pipelines, and monitoring, ensuring reliable and scalable cloud solutions.
    • Transitioned focus to frontend development with Angular and React, quickly becoming a go-to engineer for React ecosystem adoption and best practices.
    • Leveraged full-stack background to make informed architectural decisions on tools and libraries, balancing DX, performance, and maintainability.
    • Collaborated cross-functionally to deliver responsive, user-centric UIs, laying the groundwork for modern frontend practices within the team.
  • Community & Open Source
    Full Stack Developer
    • Open Source Contributor → Contributed to UI libraries and frontend tooling projects, sharing reusable components and improvements with the community.
    • Technical Blog (No Country for Geeks) → Wrote articles on React, performance optimization, and frontend best practices, making technical concepts accessible to a wider audience.
    • Workshops & Talks → Delivered workshops on frontend development and modern web practices, promoting knowledge-sharing and continuous learning.