Hi, my name is

Celsius Emilio Aray

Senior Frontend Engineer

Architecting scalable, performance-driven web experiences.

8+ years building enterprise-grade applications with React.js, React Native, Next.js, and TypeScript measurable business impact

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About Me

As a Senior Frontend Engineer, I specialize in solving complex technical challenges that others struggle with. My approach combines deep architectural thinking with pragmatic execution—whether it's rescuing stalled projects, optimizing performance by 60%, or modernizing legacy systems.

I've led frontend architecture for AI-powered SaaS platforms, implemented comprehensive testing strategies with Jest and Playwright, and mentored teams to adopt best practices in performance, security, and scalability. My expertise spans micro-frontends, GraphQL streaming, and cloud-native deployments.

Beyond writing code, I focus on building systems that scale—both technically and organizationally. I believe in clean architecture, automated testing, and creating developer experiences that empower teams to move fast without breaking things.

Core Strengths

▹Frontend Architecture - Micro-frontends, design systems, scalable patterns
▹Performance Optimization - 60%+ improvements through strategic refactoring
▹Testing & Quality - Jest, Playwright, E2E automation
▹Leadership & Mentorship - Guiding teams, code reviews, best practices
▹Problem Solving - Rescuing stalled projects, rapid issue resolution

Experience

Senior Frontend Engineer

CleverIT Group · Chile

Sep 2022 - Oct 2025

▹Pulzen.ai, an AI-powered SaaS platform with real-time dashboards
▹Delivered 60% performance improvement through optimization and resource management
▹Implemented comprehensive testing strategy with Jest and Playwright
▹Engineered platform using Next.js, GraphQL (WebSockets), Zustand, and streaming
▹Integrated conversational AI queries for DORA/SPACE metrics
▹Mentored junior developers on performance, testing, and architecture best practices

Next.js 14GraphQLTypeScriptZustandJestPlaywrightDockerGitHub Actions

Frontend Developer

Movil5 S.A · Panama

2016 - Aug 2022

▹Built and delivered 30+ web projects including PWAs and IoT integrations
▹Developed mobile apps with React Native for iOS and Android
▹Created IoT web interfaces and self-managed digital menu platform
▹Migrated and optimized apps with Next.js, Docker, and AWS S3
▹Delivered OCR/QR integrations for enterprise clients

ReactNext.jsReact NativeTypeScriptAWS S3DockerMQTT

Tech Stack

Technologies and tools I work with to build exceptional web experiences

Frontend

▹React.js
▹Next.js
▹TypeScript
▹JavaScript (ES6+)
▹HTML5
▹CSS3
▹Tailwind CSS

State & Data

▹Zustand
▹Redux Toolkit
▹TanStack Query
▹GraphQL
▹REST APIs
▹WebSockets

Testing & Quality

▹Jest
▹Vitest
▹Playwright
▹E2E Testing
▹Storybook
▹ESLint
▹Prettier

Architecture

▹Micro-Frontends
▹Module Federation
▹Clean Architecture
▹DDD
▹PWAs
▹Performance Optimization

DevOps & Cloud

▹Docker
▹GitHub Actions
▹AWS S3
▹AWS EC2
▹CI/CD
▹Vercel

Tools & Others

▹Git
▹Vite
▹Webpack
▹PNPM
▹Node.js
▹Express
▹Fastify

Case Studies

Deep dives into complex technical challenges and their solutions

Pulzen.ai

AI-Powered Engineering Productivity Platform

2022 - 2025

Challenge

Build a real-time SaaS dashboard for engineering metrics (DORA/SPACE) with conversational AI capabilities, requiring enterprise-scale performance and reliability.

Solution

→Architected frontend using Next.js with Server Components and streaming for optimal performance
→Implemented GraphQL with WebSockets for real-time data synchronization across dashboards
→Built conversational AI interface enabling stakeholders to query metrics through natural language
→Designed modular component architecture with Zustand for predictable state management
→Established comprehensive testing strategy with Jest and Playwright, automating E2E workflows

Impact

✓60% performance improvement through standalone deployments and resource optimization

✓Enabled controlled beta rollouts with feature flags and progressive enhancement

✓Achieved enterprise-scale reliability with automated regression testing

✓Delivered real-time insights through streaming architecture and WebSocket integration

Next.jsGraphQLWebSocketsZustandTypeScriptJestPlaywrightDockerGitHub Actions

GroowCity

Critical Migration & Performance Rescue

2024

Challenge

Inherited a failing Next.js 11 project with broken deployments, dependency conflicts, and performance issues. Previous teams struggled for 4 months without resolution. Client needed urgent fixes to launch.

Solution

→Conducted comprehensive technical audit identifying root causes: outdated Next.js Image component, conflicting dependencies, and deployment configuration issues
→Executed strategic migration from Next.js 11 to 15, resolving breaking changes systematically
→Fixed Image component implementation, optimizing for performance and Core Web Vitals
→Resolved dependency conflicts through careful version management and testing
→Rebuilt deployment pipeline with proper environment configuration and CI/CD automation

Impact

✓Solved in 1 month what others couldn't fix in 4 months

✓Recognized by CleverIT's Chief Officer for exceptional problem-solving

✓Enabled successful product launch with stable, performant application

✓Established maintainable codebase with clear upgrade path

Next.js 15ReactTypeScriptDockerAWSCI/CD

React Native Ecosystem

Mobile Performance & Cross-Platform Excellence

2022 - 2024

Challenge

Multiple React Native projects requiring version upgrades, dependency resolution, and performance optimization in sensitive production environments (university systems, retail apps). Needed to deliver stable mobile experiences while integrating advanced features like OCR and QR scanning.

Solution

→Executed careful version upgrades across React Native ecosystem, managing breaking changes between native modules and JavaScript packages
→Resolved complex dependency conflicts through systematic testing and version management
→Implemented performance optimizations: lazy loading, memory management, and bundle size reduction
→Integrated OCR and QR scanning capabilities for retail applications (Jumbo Chile)
→Built PWA solutions alongside native apps for broader platform support and offline capabilities
→Developed Welcome to Rocha mobile app with cross-platform iOS/Android deployment

Impact

✓Delivered stable mobile experiences for Universidad de San Sebastián with zero critical bugs

✓Enabled OCR/QR functionality for Jumbo retail operations, improving checkout efficiency

✓Improved app performance by 40% and reduced crash rates significantly

✓Established upgrade patterns and documentation for future maintenance

React NativeTypeScriptiOSAndroidPWAOCR/QRExpo

Insights & Experiments

Lessons learned from real-world projects and technical explorations

Micro-Frontends at Scale

Lessons learned implementing Module Federation with Webpack 5 for enterprise applications. Key insights on shared dependencies, versioning strategies, and deployment orchestration.

ArchitectureWebpackModule Federation

Vite vs Webpack: Migration Strategy

Practical experience migrating large codebases from Webpack to Vite. Performance gains, compatibility challenges, and when to make the switch.

Build ToolsPerformanceDX

Testing Philosophy: Beyond Coverage

Why 100% test coverage doesn't guarantee quality. Building effective testing strategies with Jest and Playwright that catch real bugs and enable confident refactoring.

TestingQualityBest Practices

AI Integration Patterns

Integrating conversational AI into React applications. Handling streaming responses, managing state, and creating intuitive user experiences for AI-powered features.

AIReactUX

Electron for Desktop Apps

Building cross-platform desktop applications with Electron and React. Balancing web technologies with native capabilities, security considerations, and distribution strategies.

ElectronDesktopCross-platform

Next.js 15: Migration Insights

Real-world experience upgrading from Next.js 11 to 15. Breaking changes, performance improvements, and strategies for minimizing disruption in production applications.

Next.jsMigrationPerformance

Let's Work Together

I'm always interested in hearing about new opportunities, challenging projects, and collaborations.