Sebastian Mateo

EternallyStream

Senior Full Stack Developer (2024 - Present)

• Designed and developed an API to connect ProtoHologram avatars with OpenAI, enabling unique AI-driven personalities.
• Integrated LLM-based responses into dynamic avatar interactions, improving engagement.
• Deployed and managed the service on Heroku, ensuring high availability and scalability.

BabyCenter

Senior Full Stack Developer (2018 - Present)

BabyCenter is the world's number one digital parenting resource, reaching millions of new and expectant parents monthly through global websites, mobile apps, and online communities. Technologies: React.js, GraphQL.js, Node.js, MySQL, AWS, Java Spring, and more.

• Led the development and enhancement of React.js and Next.js applications, improving performance and scalability.
• Developed GraphQL APIs and optimized Node.js services for efficient data retrieval.
• Architected cloud-based solutions on AWS, utilizing services like EC2, RDS, and Lambda.
• Created AI-powered text summarization features using OpenAI for article/community content.
• Maintained and modernized six legacy systems built in Java Spring Boot.
• Led migration efforts for BabyCenter’s US and international sites, transitioning to React, GraphQL, and Next.js.
• Optimized SEO and SSR performance, improving user experience and site rankings.
• Resolved critical bugs and performance issues on a high-traffic, consumer-facing website.

The Rounds

Senior Full Stack Developer (2022 - 2023)

The Rounds is a zero-waste refill and delivery service of household essentials. Technologies: React.js, GraphQL.js, Node.js, PostgreSQL, AWS.

• Enhanced client experience through the integration of innovative features and functionalities in their web applications.
• Optimized front-end code through the application of best software practices, significantly improving its maintainability and readability.
• Designed and implemented a product recommendation system based on AI custom Algorithm, taking in consideration users buying behavior.

Hollywood Spill, LLC

Android Developer (2018 - 2018)

Worked as a lead Android Engineer to build a native application for a streaming game/quiz show. Technologies: Android/Kotlin, iOS, Phoenix WebSockets.

• Implemented an Android app based on an existing iOS app.
• Implemented an event-driven design based on WebSockets.
• Fixed the Phoenix WebSockets connection and reconnection in the Android and iOS apps.
• Learned and adapted new technologies, including Kotlin, Swift, and Python, to meet specific client requirements quickly.

Inpoint

Senior Java Developer (2017 - 2018)

Aon Inpoint is the management consulting and advisory arm of Aon, the world’s leading professional services firm on Risk, Retirement, and Health. Technologies: Java Spring Boot, PostgreSQL, React.js.

• Led the back-end development for a system that dealt with complex business logic.
• Created unit tests with more than 90% code coverage.
• Helped the project manager by leading the daily meeting calls.

Other Experience

• Pyxis (2013 – 2017): Built modern React.js & Spring Boot applications for various industries.
• Inmind (2009 – 2014): Developed mobile banking web apps and multimedia recognition systems.
• Tata Consultancy Services (2006 – 2009): Worked on Java EE enterprise systems.