Open to opportunities

Cristian Fonseca Comas

@cristianfonsecacomas

Message

Tech Lead and Senior Frontend Engineer building scalable, AI-powered products.

Brazil

Message

What I'm looking for

I want to lead frontend teams, deliver scalable React/Next.js products on AWS, and build AI-powered features. I’m looking for a culture of ownership, Agile execution, and strong security/performance standards.

I’m a Tech Lead and Senior Frontend Engineer with 4+ years building scalable applications for 5M+ users. I’ve led migrations, performance initiatives, and AI feature delivery across B2C and B2B platforms, with a strong focus on measurable outcomes.

At Evaluar.com, I led a 5-person team and reduced the development cycle by 50% through Agile methodologies and AWS optimization. I also achieved a 670% payment retention increase by implementing an embedded gateway with fraud detection algorithms, and boosted report sales by 300% by building AI-powered CV enhancement using GPT and custom scraping technologies.

Earlier, I served as Frontend Tech Lead, rebranding a B2C platform for 10K+ concurrent users with real-time proctoring and multi-authentication, while reducing fraud attempts by 85% via advanced monitoring. I’m motivated by shipping high-quality, secure experiences—supported by React/Next.js ecosystems, AWS architecture, testing discipline (Jest/Cypress), and AI agent solutions using LangGraph.

Experience

Work history, roles, and key accomplishments

Current

Tech Lead

Current

Evaluar.com

Feb 2025 - Present (1 year 4 months)

Led a 5-person team and reduced the development cycle by 50% using Agile methodologies and AWS optimization. Implemented an embedded gateway with fraud detection algorithms that drove a 670% payment retention increase and increased report sales by 300%.

Next.js TypeScript NestJS AWS Lambda SQS DynamoDB Fraud Detection LangGraph PostgreSQL

Frontend Tech Lead

Evaluar.com

Mar 2024 - Feb 2025 (11 months)

Led B2C platform rebranding, implementing multi-authentication and real-time proctoring for 10K+ concurrent users. Improved security by reducing fraud attempts by 85% and increased performance by 40% through optimization and caching strategies.

React Next.js TypeScript Cloudfront S3 PostgreSQL Real Time Proctoring Security Monitoring

Senior Frontend Developer

Evaluar.com

Oct 2022 - Mar 2024 (1 year 5 months)

Migrated a B2B platform from Vue 2 to Nuxt 3, completing an 18-month project 3 weeks ahead of schedule. Delivered rebranding results that increased enterprise client acquisition by 300% and reduced load time by 60%.

Vue.Js Nuxt.Js TypeScript GraphQL Migration Performance Optimization

Junior Frontend Developer

Evaluar.com

Nov 2021 - Oct 2022 (11 months)

Contributed to React and Vue ecosystems and delivered 95% of features on time. Built an automated testing suite that reduced bug reports by 60%.

React Vue.Js JavaScript Jest Cypress Automated Testing

Senior Frontend Engineer

Freemance

Jun 2021 - Nov 2021 (5 months)

Collaborated with a 5-person team on a freelance project, contributing to frontend architecture decisions and performing PR reviews across React and Vue.js codebases. Optimized performance, reducing load times from 8 seconds to under 2 seconds.

React Vue.Js GraphQL Frontend Architecture Code Review Performance Optimization

Education

Degrees, certifications, and relevant coursework

Julio A. Mella PreUniversity

Pre-University program, Pre-University

2016 - 2019

Grade: Top 10% of class (90+ average)

Activities and societies: Programming competition participant.

Completed the Julio A. Mella pre-university program in Cuba (2016–2019), ranking in the top 10% of the class (90+ average) and participating in programming competitions.