Leandro Vieira, Developer in Montevideo, Montevideo Department, Uruguay
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Leandro Vieira

Verified Expert  in Engineering

Front-end Developer

Montevideo, Montevideo Department, Uruguay
Toptal Member Since
May 12, 2022

Leandro is a front-end engineer with more than 15 years of experience, focusing on developing rich interfaces and seamless user experiences. He is a perfectionist regarding design and enjoys working closely with product, design, and back-end teams. Leandro has been exploring the React ecosystem for the last four years, evolving along with the core front-end tools.


React, JavaScript, Front-end, CSS3, Agile, REST, Jira, Jest, Storybook...
An Online Freelance Agency
React, Front-end, TypeScript, React Router, React Query, Microsoft Teams, REST...
Front-end, Communication, JavaScript, jQuery, Sass, CSS3, Drupal, BigCommerce...




Preferred Environment

React, Sass, Visual Studio Code (VS Code), Windows, Google Drive, Agile, Git, Webpack, Babel, Front-end, APIs

The most amazing...

...product I’ve designed and developed is a front-end app to manage operations in one of the top US based electrical companies, with more than 6,000 employees.

Work Experience

Senior Front-end Engineer

2021 - PRESENT
  • Led the definition of a new standard for the front-end technologies and tools to be used in the organization.
  • Designed the new SaaS platform's front-end architecture and the tech stack to be used.
  • Tasked with training the front-end teams in the organization in accessibility markup and Accessible Rich Internet Applications (ARIA) standard implementation after a successful experience applying it myself.
  • Collaborated in technical interviews to choose new senior front-end candidates to grow the team, and was tasked to train them.
  • Surpassed the expectations on every sprint, regarding the amount of work completed and its quality.
  • Contributed ideas and advice during the design phase, foreseen implementation and usability issues, and possible improvements with the user experience.
Technologies: React, JavaScript, Front-end, CSS3, Agile, REST, Jira, Jest, Storybook, Playwright, Sass, JSX, Accessible Rich Internet Applications (ARIA), Responsive UI, Figma, React Query, React Router, User Experience (UX), CSS, HTML, Git, Responsive Layout, APIs, Next.js

Senior Front-end Engineer

2021 - 2021
An Online Freelance Agency
  • Defined the layout, visual design, and front-end architecture, including the technologies and patterns to be used, for a front-end app to manage operations in one of the top US-based electrical companies, with more than 6,000 employees.
  • Developed maps, calculators, SVG animations, rich interactions, and other small apps for Siege Media, a cutting-edge digital content agency based in California.
  • Created a browser extension to extract insights about prospective clients and competitors' websites, with several valuable metrics and highlights, within the digital marketing industry.
  • Conceived and created an interface that integrates seamlessly with the company's workflow to display, filter, and search past and feature projects to measure and take advantage of their work history.
  • Designed and developed a React blog post generator that creates a combination of HTML, CSS, and JavaScript through a simple UI that doesn't require the user to know to code and saves coders time with repetitive tasks.
  • Conducted interviews to grow two different front-end teams.
Technologies: React, Front-end, TypeScript, React Router, React Query, Microsoft Teams, REST, JavaScript, CSS3, Jest, Sass, Pug, Webpack, Babel, User Experience (UX), UI Design, Web UI, Data Visualization, CSS, D3.js, HTML, Git, React Redux, Firebase, Responsive Layout, APIs

Senior Front-end Developer & Lead/Lead UX Designer

2009 - 2020
  • Developed and maintained the front end of dozens of websites and web apps, from small to large.
  • Trained front-end recruits and provided direction, supervision, and motivation for the three to five people on the front-end team, as well as outsourced personnel.
  • Advised and defined front-end standards and practices within the company through several stages of radical technological change over the years. Managed to improve code and component’s modularity, scalability, and efficiency.
  • Helped dozens of clients define their business goals, digital communication, and brand strategies.
  • Worked as a backup back-end developer with technologies and tools outside my specialties, like PHP, MySQL, Python, Google Ads, Facebook Ads, Microsoft Power BI, Microsoft SQL Server, and others.
  • Designed hundreds of websites, applications, animations, and other pieces, including wireframes. Finished designs, for clients in media, telecommunications, retail, health, education, government, and real estate, among others.
Technologies: Front-end, Communication, JavaScript, jQuery, Sass, CSS3, Drupal, BigCommerce, D3.js, GraphQL, MySQL, PHP, Photoshop CC, Axure RP Pro, Illustrator CC, User Experience (UX), UI Design, Web UI, Data Visualization, CSS, React, HTML, Git, DataViz, Responsive Layout, Tailwind CSS, APIs

Web Developer

2010 - 2014
Grande Gandhi
  • Led the development and web design within the agency, with strategies encompassing websites, mobile apps, email marketing, social network marketing, internet advertising, and the internet of things (IoT).
  • Advised clients and colleagues in the definitions of digital strategy for each project.
  • Developed CMS EXEC, Drupal, WordPress, and Joomla, and static landing pages with HTML, CSS, and JavaScript, including for the agency's pages.
  • Designed many highly aesthetic and animated websites for small local businesses.
  • Configured and managed the servers for the client's websites.
Technologies: JavaScript, jQuery, Sass, Drupal, WordPress, PHP, MySQL, DevOps, HTML5, Photoshop CC, Illustrator CC, Adobe Animate, Apache, User Experience (UX), UI Design, Web UI, CSS, HTML, D3.js, DataViz, Responsive Layout, Front-end

React SaaS platform

Developed an application is used to define the flow of communication between the B2C software and tens of millions of users and analyze the data coming from those interactions.

It consists of a responsive and animated UI that displays and manages four entities (organization, client, application, and dashboard). It allows editing, filtering, sorting, bookmarking, cloning, and loading of external applications to further display and manage instances of those entities.

The front-end was done by two front-end engineers in close communication with the back end, product, design, and QA teams.

I designed the architecture and developed the UI, engaged through the project's lifecycle.

Scrolly - Telling and Interactive Data Visualizations

Two React-based interactive articles, adapting academic papers from the American Enterprise Institute. I proposed a design based on the original material and developed visualizations sensitive to the user scrolling through the page and other interactions. They contain a few animated charts and maps, alternating with texts to be read.

Internal Operations Managment Platform

Worked with an application to manage operations in one of the top US-based electrical companies, with more than 6,000 employees.

It manages hundreds of thousands of operations with a complex structure of clients, users, projects, packages, orders, reports, and other entities with different degrees of interrelation.

The platform allows different modes to visualize the entities, such as tables and cards, in a fully responsive design where fields can be edited on the spot.

The client application is connected to a back end written in .NET through REST APIs.

I designed the front-end architecture, built the UI, and wrote the tests.

Wikidata & Wikimedia JSON Generator

Created a method for importing data from Wikimedia, Wikipedia, and Wikidata and exporting it as JSON files.

It's beneficial to generate small or medium curated data sets from simple names, words, and wiki IDs.

Data about places associated with the selected items is loaded independently, with geographical coordinates, on maps.

GeoMap Maker

Developed an online custom world-map maker with 87 projections to choose from, various datasets, and custom options. It allows to select a dataset, toggle the layer's visibility, and change colors. The result can be exported as an SVG or PNG image.

Pattern Extractor

Built a web app as a personal project where I can extract fragments from text, such as emails, phone numbers, URLs, words, and custom expressions.

The result can be sorted and customized before being copied to a clipboard.

Gaze of Time

Created a way to visualize hundreds of thousands of entities from Wikipedia and Wikidata in a visual and chronological fashion.

Each item can be used as the reference point of a visualization displaying other related items, with taxonomies automatically deducted from the available data.


React, D3.js, React Router, jQuery, LocalStorage, Wikipedia API, JSON API, Mantine, React Redux, Three.js, Playwright, Mustache, Node.js, React Query


JSX, Basecamp, Slack, Git, Lucidchart, Axure RP Pro, Prettier, Webpack, Babel, Jira, Adobe Flash, GitLab, GitHub, Mailchimp, DataViz, Figma, Photoshop CC, Jekyll, Stencil.js, Microsoft Teams, Adobe Animate, Illustrator CC, Apache


JavaScript, Sass, HTML, CSS3, ECMAScript (ES6), HTML5, CSS, TypeScript, Pug, Regex, GraphQL, PHP


Functional Programming, Responsive Layout, REST, Web UX Design, Agile, Scrum, BEM, UI Design, DevOps


Drupal, Visual Studio Code (VS Code), WordPress, BigCommerce, Firebase




Redux, Jest, Bootstrap, Material UI, Tailwind CSS, Next.js


Front-end Architecture, Front-end Development, Front-end Design, Front-end, User Interface (UI), Responsive UI, Drupal Themes, Storybook, CSS3 Animation, Zustand, ESLint, TopoJSON, Google Drive, Communication, Accessible Rich Internet Applications (ARIA), Data Visualization, Animation, User Experience (UX), Web UI, APIs, QGIS, SVG Animation, Writing & Editing, BigCommerce Stencil Design, Chrome Extensions, Firefox Extensions, Edge Extensions, Scraping, CSS Modules, Scroll Animations

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