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I’m Oliver Alonso, a Senior Frontend Engineer based in Cadiz, Spain, with 11 years of experience specializing in React ecosystems and high-performance user interfaces. I’m proficient in React, Next.js, and Vite, and I design systems and testing strategies to ship robust features quickly. I’ve led frontend development across multiple companies, mentored engineers, and built production-grade apps with atomic design patterns and end-to-end feature ownership. I founded CrimeMapX.com while maintaining hands-on technical leadership and coding, delivering impactful interfaces and scalable architectures.…I’m Oliver Alonso, a Senior Frontend Engineer based in Cadiz, Spain, with 11 years of experience specializing in React ecosystems and high-performance user interfaces. I’m proficient in React, Next.js, and Vite, and I design systems and testing strategies to ship robust features quickly. I’ve led frontend development across multiple companies, mentored engineers, and built production-grade apps with atomic design patterns and end-to-end feature ownership. I founded CrimeMapX.com while maintaining hands-on technical leadership and coding, delivering impactful interfaces and scalable architectures.

Oliver Alonso

Full Stack Developer, Front-End Developer, Back-End Developer, +2

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I’m Oliver Alonso, a Senior Frontend Engineer based in Cadiz, Spain, with 11 years of experience specializing in React ecosystems and high-performance user interfaces. I’m proficient in React, Next.js, and Vite, and I design systems and testing strategies to ship robust features quickly. I’ve led frontend development across multiple companies, mentored engineers, and built production-grade apps with atomic design patterns and end-to-end feature ownership. I founded CrimeMapX.com while maintaining hands-on technical leadership and coding, delivering impactful interfaces and scalable architectures.…I’m Oliver Alonso, a Senior Frontend Engineer based in Cadiz, Spain, with 11 years of experience specializing in React ecosystems and high-performance user interfaces. I’m proficient in React, Next.js, and Vite, and I design systems and testing strategies to ship robust features quickly. I’ve led frontend development across multiple companies, mentored engineers, and built production-grade apps with atomic design patterns and end-to-end feature ownership. I founded CrimeMapX.com while maintaining hands-on technical leadership and coding, delivering impactful interfaces and scalable architectures.

Available to hire

I’m Oliver Alonso, a Senior Frontend Engineer based in Cadiz, Spain, with 11 years of experience specializing in React ecosystems and high-performance user interfaces. I’m proficient in React, Next.js, and Vite, and I design systems and testing strategies to ship robust features quickly.

I’ve led frontend development across multiple companies, mentored engineers, and built production-grade apps with atomic design patterns and end-to-end feature ownership. I founded CrimeMapX.com while maintaining hands-on technical leadership and coding, delivering impactful interfaces and scalable architectures.

Skills

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Expert

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Intermediate

Work Experience

Lead Software Engineer at 90poe.io

November 1, 2022 - Present

Architected and built a responsive React frontend using Next.js and Vite, implementing a modern design system with TypeScript for type safety across 50+ reusable UI components. Delivered real-time data visualizations and integrated monitoring to reduce MTTR by 70%. Led migration from monolithic React to a micro-frontend architecture across four squads, improving team autonomy and UX consistency.

Founder at CrimeMapX.com

June 1, 2025 - Present

Founded CrimeMapX.com to build a full-stack crime analytics platform. Led architecture for SSR-based frontend with Next.js/React and implemented advanced SEO, caching with GraphQL APIs, and a visually rich data visualization layer using D3.js. Achieved real-time UI updates and deployed serverless edge functions for global distribution across 285+ cities.

Lead Software Engineer at 0XA Tech

July 1, 2022 - November 1, 2022

Built a full-stack Web3 platform using Next.js/React with advanced SSR and hydration to optimize SEO and performance. Architected a responsive frontend with React Hooks and TypeScript; integrated 50K+ daily transactions with a seamless Web3 wallet flow.

Senior Software Engineer at Casebook PBC

May 1, 2021 - July 1, 2022

Built a responsive React frontend with GraphQL BFF architecture; implemented optimized query patterns with caching that reduced backend response time by 42% and improved real-time data synchronization. Designed a modular component library with hooks across complex social services workflows.

Senior Software Engineer at Feedr

May 1, 2020 - May 1, 2021

Built a React/TypeScript frontend with a GraphQL API implementing CQRS for an office- food ordering platform. Designed a modular design system and improved UI performance, enabling faster feature delivery and a smoother user experience.

Senior JS Engineer at Spotahome

February 1, 2019 - April 1, 2020

Built a React/TypeScript frontend for property management with Domain-Driven Design; developed a responsive landlord web app and a React Native mobile app, enabling landlords to list properties, upload photos, and track analytics with real-time synchronization. Implemented a BFF layer consolidating 8 microservices, reducing frontend calls and improving page load times.