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Leonardo SánchezLS

Leonardo Sánchez

Sr. Frontend Web Developer

€480/day
Berlín, DE
3-7 years

Average response time: 1 hour

About Leonardo

Senior Frontend / Full Stack Developer helping startups and digital businesses build fast, scalable, and user-focused web products. My core stack includes React.js, Next.js, TypeScript, JavaScript, Node.js, MongoDB, and modern frontend architecture. I work on SaaS platforms, fintech products, e-commerce systems, dashboards, internal tools, and custom web applications, always with a strong focus on performance, maintainability, and clean user experience. I can support projects from UI implementation to backend integration and feature delivery. If you are looking for a reliable developer who communicates clearly, understands product needs, and delivers production-ready solutions, let’s connect.
  • Spanish

    Native or bilingual

  • English

    Fluent

  • German

    Basic

Can work on-site
Berlín (up to 50km)

Experience

  • Libélula Soft
    Sr. Frontend Web Developer
    BANKING AND INSURANCE
    November 2023 - Today (2 years and 9 months)
    Quito, Ecuador
    Developed the frontend for a financial services platform using React, Next.js, and React Native. Optimized user workflows through effective state and form management with React Hook Form and Redux, reducing user errors and improving form completion rates. Built and refined reusable UI components with Tailwind CSS and React, accelerating feature delivery and maintaining design consistency.
    Reduced regression bugs by 50% during release cycles by implementing automated testing with Cypress, Playwright, and Jest. Improved code quality and reduced integration issues by adopting TypeScript for strict typing and reliable API communication within a MERN stack. Enhanced backend integration and data flow using Laravel and C#, improving overall platform responsiveness and consistency.
    React.js Typescript Next.js Node.js MongoDB
  • Pickatale -
    Sr. Full Stack Engineer
    E-COMMERCE
    March 2023 - November 2023 (8 months)
    Quito, Ecuador
    EdTech platform helping children learn new languages and encouraging reading through interactive digital books. Engineered modular components with React, Next.js, Styled Components, and TypeScript, reducing page load times by 30%. Improved media content delivery and backend automation by integrating Azure Blob Storage and Azure Functions, resulting in a 45% decrease in server load. Automated Docker-based CI/CD workflows to optimize deployments, reducing production bugs. Boosted system performance through optimized MongoDB queries and in memory caching, reducing data retrieval times by 40%. Designed and maintained robust GraphQL APIs using Apollo and Node.js, supporting increased concurrency during peak classroom usage. Adapted the web application for mobile platforms using React Native, enabling cross-platform compatibility and reducing development time by reusing over 80% of the codebase.
    MongoDB Typescript Next.js GraphQL Node.js
  • Jalasoft
    Ssr. Full-stack Developer
    TECH
    January 2021 - January 2023 (2 years)
    Quito, Ecuador
    SaaS and ERP development for enterprise-grade HR and asset management systems. Developed a centralized authentication system using Node.js and React, reducing login-related user errors by 35% and improving session reliability within modules. Built accessible and responsive UI components using Next.js and Tailwind, increasing module accessibility and improving user experience between desktop and mobile platforms.
    Designed a browser-based video interview tool using NestJS, boosting HR team engagement and supporting asynchronous evaluations. Tested and validated the permission stepper component using Jest, ensuring unit test coverage and reducing onboarding-related bugs in video workflows. Optimized MongoDB clusters for high-traffic scenarios, reducing query latency and ensuring reliable performance through datasets exceeding 10 million records. Deployed automated CI/CD pipelines using Docker and GitHub Actions, reducing rollback incidents and bugs..
    MongoDB Node.js Docker React.js C#

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Education

  • Curso Básico de Seguridad Informática para Empresas
    React
    Curso Básico de Seguridad Informática para Empresas
  • Bachelor's in Software Engineering
    Universidad Tecnológica Israel
    2022
    Bachelor's in Software Engineering

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