Fabio Marcellus

Spearheaded migration of a large-scale Angular 7 app to React/TypeScript, improving maintainability and reducing build times by 74%. Directed upgrade (Angular v7 → v18) while transitioning new feature development to React, ensuring smooth migration with zero downtime. Introduced ESLint and stricter typing, cutting production runtime errors by 15%. Optimized API data fetching with React Query, improving landing page load speeds by 2.5 seconds and reducing payload size by 50MB. Boosted accessibility from 74 → 98 (WCAG AA). Built reusable React components from Figma, accelerating new feature delivery by 30%. Increased test coverage by 20% with Jest and React Testing Library, reducing post-release bug frequency.

Front End Software Engineer at Katmai

Contributed to new React/Next.js features for a client-facing analytics platform, improving dashboard load time by 20% with bundle splitting and caching. Built and documented reusable UI components in Storybook, enabling faster adoption by other engineers and reducing duplicate code. Collaborated with backend engineers to refine GraphQL queries, reducing data transfer size by 15% on key endpoints. Improved accessibility on high-traffic forms, raising Lighthouse accessibility score from 82 to 90. Presented complete features during biweekly client demos, strengthening transparency and stakeholder alignment.

Front End Software Engineer at Citi

Spearheaded migration of a large-scale Angular 7 application to React/TypeScript, improving maintainability and reducing build times by 74%. Directed upgrade (Angular 7 → Angular 8) while migrating new feature development to React, ensuring smooth migration with zero downtime. Introduced ESLint and stricter typing, cutting production runtime errors by 15%. Optimized API data fetching with React Query, improving landing page loads by 2.5 seconds and reducing payloads by 50 MB. Boosted accessibility from 74 to 98 (WCAG AA). Built reusable React components from Figma, accelerating feature delivery by 30%. Coordinated API integration with Node.js services, reducing average API error rate by 15%. Drove adoption of Jest + React Testing Library, increasing test coverage from 60% to 85% and shortening QA cycles by 25%.

Front End Software Engineer at Katmai

Contributed to new React/Next.js features for a client-facing analytics platform; improved dashboard load time by 20% with bundle splitting and caching. Built and documented reusable UI components in Storybook, enabling faster adoption by other engineers and reducing duplicate code. Collaborated with backend engineers to refactor GraphQL queries, reducing data transfer size by 15% on key endpoints. Improved accessibility on high-traffic form pages, raising Lighthouse accessibility score from 82 to 90. Presented completed features during biweekly client demos, strengthening transparency and stakeholder alignment.

Front End Developer at Tech Solutions

Delivered responsive dashboards in React/Next.js, enabling clients to visualize real-time data with minimal latency. Designed real-time API integrations with Node.js, cutting resolution time for client-reported account issues by 45%. Expanded Cypress E2E testing, increasing automated coverage from 60% to 85% and shortening QA cycles by 25%. Standardized linting/commit hooks with ESLint + Husky, reducing PR review issues by 30%. Partnered with UX designers to refine components from Figma, improving design-to-code turnaround by 20%.