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Leonardo Massaroli
Verified Expert in Engineering
Front-end Developer
Buenos Aires, Argentina
Toptal member since October 11, 2022
Bio
Leonardo is a software engineer with over six years of experience developing web and mobile applications for startups and established companies. As the founder of Sophie Games, he built Lines of Battle, a multiplayer strategy game that reached 175,000 registered users within 12 months of development in 2024. His expertise lies in full-stack development, leveraging technologies such as TypeScript, PostgreSQL, and AWS to create scalable, user-focused solutions.
Portfolio
Sophie Games
Amazon Web Services (AWS), Android, TypeScript, Steam, Node.js, AWS Lambda...
InsightRX, Inc.
Node.js, React, SQL, MongoDB, MySQL, NoSQL, PostgreSQL, Docker
LastRev
CSS, React, TypeScript, Next.js, Pixel Perfect, JavaScript, Contentful, GraphQL...
Experience
- JavaScript - 6 years
- Web Development - 6 years
- Full-stack - 3 years
- React - 3 years
- TypeScript - 3 years
- Node.js - 3 years
- Express.js - 2 years
- Next.js - 1 year
Preferred Environment
Slack, GitHub, TypeScript, React, Node.js, JavaScript, Amazon Web Services (AWS)
The most amazing...
...project I've created is Lines of Battle, a video game that gained over 175,000 registered users in its first 12 months.
Work Experience
Founder and Full-stack Developer
2024 - PRESENT
Sophie Games
- Founded Sophie Games and developed Lines of Battle, a WeGo multiplayer strategy game, growing it to 175,000 registered users and 50,000 monthly active users within 12 months of development.
- Designed and implemented a freemium model with in-app purchases, integrating PayPal and Google Play Billing APIs, which significantly increased company revenue.
- Designed and deployed a scalable AWS infrastructure using Lambda, PostgreSQL, and EC2.
- Enhanced gameplay features based on user feedback.
Technologies: Amazon Web Services (AWS), Android, TypeScript, Steam, Node.js, AWS Lambda, Amazon EC2, Docker, PostgreSQL, PayPal API, PayPal, Google Play Console, Google Play Billing API
React and TypeScript Full-stack Developer
2023 - 2025
InsightRX, Inc.
- Developed an application that displays patient statistics graphs to pharmacists.
- Migrated old legacy code to new code using the best technologies on the market, significantly increasing the maintainability of the application.
- Helped colleagues when they needed it, so I could unblock them in areas where I had knowledge of how they worked.
Technologies: Node.js, React, SQL, MongoDB, MySQL, NoSQL, PostgreSQL, Docker
Front-end Developer
2023 - 2023
LastRev
- Utilized Contentful as a CMS and implemented GraphQL for efficient data retrieval from the CMS to the front end, enhancing website performance and reducing content delivery time.
- Developed and implemented new features and components, concurrently managing multiple client environments and improving project efficiency.
- Resolved bugs, ensuring seamless user experiences and reducing customer requests.
Technologies: CSS, React, TypeScript, Next.js, Pixel Perfect, JavaScript, Contentful, GraphQL, REST
Senior Front-end Developer
2022 - 2022
AccessPay
- Developed and maintained the front end of new administrative pages from scratch using TypeScript.
- Provided support to my teammates and did pair programming with them in those parts that were needed.
- Tracked and fixed bugs using Jira as a reporting tool.
Technologies: Angular, TypeScript, Jira, Slack, Git, Azure, ECMAScript (ES6), Windows, Web Applications, Web Development, Front-end Development, Startups, Single-page Applications (SPAs)
Senior Front-end Developer
2021 - 2022
Intive
- Started a new team from scratch for a customer dedicated to maintaining and improving a free ad-supported streaming platform.
- Made the existing app work on a new branch of devices. Solved bugs and created unit tests to ensure all devices functioned correctly.
- Improved the app accessibility by migrating the JavaScript text to speech (TTS) used before for Accessible Rich Internet Applications (ARIA) labels.
Technologies: React, TypeScript, Redux, Redux-Saga, CSS, HTML5, Sass, Git, HTML, REST APIs, APIs, JavaScript, DevOps, CI/CD Pipelines, Amazon Web Services (AWS), Slack, Jest, Front-end, GitHub, Visual Studio Code (VS Code), ECMAScript (ES6), Windows, Jira, Unit Testing, Web Applications, Web Development, Front-end Development, Enterprise, Single-page Applications (SPAs), REST
Semi-senior Front-end Developer
2020 - 2021
Globant
- Listed the information of the company's customers and modified it by creating a back office app for a customer dedicated to an agriculture eCommerce.
- Designed the back office app from scratch using Confluence, Jira, and Figma and developed it in React using the Next.js framework.
- Collaborated with the team and back-end developer to sync the front end with the back end through an application programming interface (API).
- Promoted to semi-senior advance role thanks to my good performance in the project and satisfying the client's needs.
Technologies: JavaScript, React, Next.js, Styled-components, CSS, HTML5, Git, HTML, Postman, Figma, REST APIs, APIs, DevOps, CI/CD Pipelines, Slack, Jest, Front-end, Visual Studio Code (VS Code), ECMAScript (ES6), Material UI, Windows, Jira, Unit Testing, Web Applications, Web Development, Front-end Development, Startups, Single-page Applications (SPAs), REST
Full-stack Engineer
2017 - 2021
Independencia Juego
- Reached more than 1,000 users on a multiplayer 3D strategy game about the independence of South America.
- Created the game from scratch by developing its front end, back end, and database using React, Node.js, and MySQL technologies.
- Migrated the app to React, which initially used HTML, CSS, and Vanilla JS.
- Applied test-driven development (TDD) for the game rules, such as combat between units, using Mocha for testing.
- Hosted the entire game on the Google Cloud Platform and then on Heroku.
Technologies: Node.js, React, TypeScript, JavaScript, Babylon.js, MySQL, Test-driven Development (TDD), Socket.IO, CSS, HTML5, Git, HTML, Full-stack, Full-stack Development, Express.js, REST APIs, APIs, WebSockets, Sockets, Slack, Front-end, Back-end, GitHub, Visual Studio Code (VS Code), Chart.js, ECMAScript (ES6), 2D Games, Games, Unit Testing, SQL, Google Cloud, Electron, Web Applications, Babel, Web Development, Front-end Development, Back-end Development, OAuth, WebGL, Desktop App Development, Startups, Single-page Applications (SPAs), REST
Software Engineer
2016 - 2019
Freelance
- Developed projects for clients and myself using technologies and good practices such as TDD, front-end and back-end development, React, React Native, TypeScript, Heroku, Node.js, MySQL, Mocha, Jest, and functional programming.
- Automated the parsing of my client's leads by developing email parsers and the back end.
- Improved the leads saving process of a client by creating a web application where the lead info is placed and then converted into JSON, capable of being saved to the MongoDB database.
Technologies: Front-end, Back-end, React, Heroku, Node.js, MySQL, Mocha, JavaScript, CSS, HTML5, Git, HTML, Postman, MongoDB, REST APIs, APIs, TypeScript, Express.js, DevOps, CI/CD Pipelines, Slack, GitHub, ECMAScript (ES6), Jira, Web Applications, GraphQL, Web Development, Front-end Development, Back-end Development, Android, Startups, Mobile App Development, React Native, REST
Experience
Goat Wars
https://www.linkedin.com/company/kodoku-studiosI worked as a full-stack developer on a video game project that involved multiple NPCs fighting each other. My responsibilities included improving and fixing existing functionality, creating new features, and migrating the project from a down CMS to a new host with a new database.
ACCOMPLISHMENTS
• Used Google Cloud and MongoDB for the migration.
• Created unit tests for the complex parts of the code.
• Fixed the players' collision system.
• Created and applied a random map generator algorithm for the game using tiles.
• Changed the players' sprite sheet from two directions to four directions.
• Added in-game chests and power-ups.
• Refactored the screens and applied React in the interfaces.
• Added the possibility to focus on a specific player in-game.
• Deployed the game in Google Cloud and applied continuous deployment to speed up the deployment process.
ACCOMPLISHMENTS
• Used Google Cloud and MongoDB for the migration.
• Created unit tests for the complex parts of the code.
• Fixed the players' collision system.
• Created and applied a random map generator algorithm for the game using tiles.
• Changed the players' sprite sheet from two directions to four directions.
• Added in-game chests and power-ups.
• Refactored the screens and applied React in the interfaces.
• Added the possibility to focus on a specific player in-game.
• Deployed the game in Google Cloud and applied continuous deployment to speed up the deployment process.
Independencia Juego
WORK DONE
• Created my own multiplayer 3D strategy game about the independence of South America from scratch.
• Developed the front end, back end, and database using React, Node.js, and MySQL technologies.
• Migrated the app to React and Babylon.js from HTML, CSS, and Vanilla JS.
Applied TDD to create quality tests and ensure that the functionality works well.
• Hosted the game on Google Cloud Platform and Heroku.
• Created my own multiplayer 3D strategy game about the independence of South America from scratch.
• Developed the front end, back end, and database using React, Node.js, and MySQL technologies.
• Migrated the app to React and Babylon.js from HTML, CSS, and Vanilla JS.
Applied TDD to create quality tests and ensure that the functionality works well.
• Hosted the game on Google Cloud Platform and Heroku.
Pixi Shooter
https://github.com/leoflood/pixi-shooterThis is a 2D demo shooter video game where the player will try to survive the enemy waves that will appear.
I created the game from scratch and developed it with React, TypeScript, and the PixiJS framework. I also designed the code structure of the entities in the game by using the composite design pattern. Finally, I applied test-driven development (TDD) for the complex parts of the code using Jest.
I created the game from scratch and developed it with React, TypeScript, and the PixiJS framework. I also designed the code structure of the entities in the game by using the composite design pattern. Finally, I applied test-driven development (TDD) for the complex parts of the code using Jest.
Ezejedrez
https://github.com/sophie-games/ezejedrezDeveloped a chess game from scratch with React Native and TypeScript. The movement of all the pieces was designed using test-driven development to ensure that all the game rules are tested, and there are no errors.
Education
2011 - 2017
Technician in Graphic Design
Escuela Técnica N°6 Fernando Fader - Buenos Aires, Argentina
Skills
Libraries/APIs
React, Node.js, Socket.IO, REST APIs, Sockets, Babylon.js, Redux-Saga, Chart.js, WebGL, PayPal API
Tools
Git, Slack, Figma, Webpack, GitHub, Expo, Mocha, Postman, Jira, Babel, ChatGPT
Languages
TypeScript, JavaScript, CSS, HTML, HTML5, ECMAScript (ES6), SQL, Sass, GraphQL
Frameworks
PixiJS, Jest, Next.js, Redux, Express.js, React Native, Material UI, Electron, Angular, Tailwind CSS, Ionic
Paradigms
Unit Testing, REST, DevOps, Test-driven Development (TDD), Desktop App Development
Storage
MySQL, MongoDB, Google Cloud, PostgreSQL, NoSQL
Platforms
Heroku, Windows, Visual Studio Code (VS Code), Amazon Web Services (AWS), Azure, Docker, Google App Engine, Android, Contentful, Steam, AWS Lambda, Amazon EC2
Other
Vite, Front-end, Back-end, Full-stack, Full-stack Development, WebSockets, Games, 2D Games, Web Applications, Web Development, Front-end Development, Back-end Development, Single-page Applications (SPAs), APIs, Composite, Styled-components, ESLint, CI/CD Pipelines, Design, OAuth, OpenAI GPT-3 API, Startups, Enterprise, Mobile App Development, Pixel Perfect, PayPal, Google Play Console, Google Play Billing API, Advertising
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