
Diego Ferreyra
Verified Expert in Engineering
Full-stack Developer
Córdoba, Cordoba, Argentina
Toptal member since January 24, 2013
Diego is a senior Angular developer with 13+ years building production web applications across healthcare, hospitality, and biotech. He specializes in Angular (AngularJS through 18+) and full-stack JavaScript with Node.js and REST APIs, and has shipped work for Royal Caribbean, Ricoh, ADS Environmental Services, and Sage Bionetworks. His recent work includes a HIPAA-compliant healthcare platform and contributions to Cline, an open-source AI coding agent.
Portfolio
Experience
- JavaScript - 14 years
- REST APIs - 10 years
- RxJS - 8 years
- Angular - 8 years
- TypeScript - 8 years
- AngularJS - 6 years
- Full-stack - 6 years
- Node.js - 6 years
Preferred Environment
Visual Studio, MacOS, GitHub, Git, NPM, Node.js, Slack, Figma, Chrome DevTools, GitHub Actions
The most amazing...
...thing I've built is an Angular and D3.js visualization helping Sage Bionetworks researchers prioritize Alzheimer's drug targets from complex biological data.
Work Experience
Technical Support Engineer
Cline Bot Inc.
- Managed technical triage and community operations for a large open-source GitHub repository, helping reduce backlog noise and improve routing of incoming issues, support requests, and feature suggestions.
- Reviewed and categorized high volumes of GitHub issues and pull requests, separating actionable bugs from support cases, stale reports, duplicates, and feature requests to keep engineering attention focused on high-impact work.
- Contributed to reducing the open issue backlog to under 350 issues by closing stale or non-actionable reports, requesting missing reproduction details, and improving issue hygiene across the repository.
- Identified root causes in reported issues through code-level investigation, helping distinguish product defects from environment-specific limitations, expected behavior, or unsupported configurations.
- Supported contributor and maintainer workflows by refining triage processes, reducing ambiguity in issue handling, and making community-reported problems more actionable for the engineering team.
- Reported weekly progress using measurable output, including dozens of issues triaged and closed, backlog decisions, and root causes identified.
Angular Developer
Stealth Technology Startup
- Developed and integrated RESTful APIs with a responsive Angular front end, enabling real-time synchronization between patient and provider management modules.
- Transformed Figma UI/UX designs into a fully responsive, production-ready web application used by over X patients and healthcare professionals.
- Collaborated with cross-functional teams (back-end, design, QA) to align API contracts, ensure scalability, and maintain a consistent design system.
- Implemented new features such as appointment scheduling, medical records display, and authentication flows, improving user satisfaction and engagement.
- Resolved critical bugs and UI inconsistencies across multiple modules, achieving a significant reduction in reported defects post-release.
- Maintained code quality standards through linting, reusable components, and peer reviews, improving long-term maintainability of the codebase.
Angular Developer
Ricoh Corporation - DSC - PortfolioSoftwareSolutions
- Developed an app for reviewing scanned rejected checks and allowing the completion of missing information or further rejecting it before the batch gets to the destination.
- Integrated the app with Ricoh platform services and management.
- Integrated the app with Mavro systems for check batch details reviewing, image processing, and report selection.
- Helped with environment and continuous integration development.
Angular Developer
Royal Caribbean
- Collaborated with the engineering and design teams to enhance the user experience of Royal Caribbean’s online booking platform, improving usability and navigation across multiple user journeys.
- Developed and deployed new Angular components and modules that streamlined travel management and booking flows, resulting in a faster and more intuitive customer experience.
- Resolved high-priority bugs and optimized performance, ensuring a stable and error-free interface for thousands of daily users.
Front-end Angular Developer
Random Games Company, Inc
- Merged five separate Angular apps into a single app for a streamlined single-page application (SPA) deployed in one environment.
- Tracked and resolved bugs using their reporting system.
- Refactored components and upgraded login authentication to support the latest blockchain wallet handlers.
Web UI Developer
ADS Environmental Services / IDEX Corp.
- Developed new features and optimized existing code using Angular.
- Identified and fixed bugs with the Jira tracking tool.
- Supported QA testing and refactored the entire application for improved performance.
Web UI Developer
IDEX
- Developed core features for a web application that puts critical data at your fingertips to support management, engineering, and operational decisions within the wastewater collection system.
- Tracked and fixed bugs using the Azure tracking environment.
- Collaborated with the back-end engineers to connect and improve the API.
Angular Engineer
AssetWorks
- Optimized maps for real-time marker updates and tracking for over 5,000 entities.
- Combined markers to show more advanced information, like type and direction, while moving.
- Improved and optimized components to avoid issues and help readability.
- Solved several performance issues with the company's Angular app.
Front-end Angular Developer
Stayafloat
- Handled all front-end development on a pre-started project and continued working and improving on it as the single developer.
- Improved the site to be mobile-first ready. Made sure all templates worked on tablets and phones.
- Created a small JSON parser for dynamic form creations.
Front-end Developer
Sage Bionetworks
- Developed and maintained the site using Angular 7.
- Built a force chart in D3 for gene network viewing.
- Developed and optimized a bar chart in DC for gene RNA values.
- Stored the gene network in MongoDB with Express.js API management.
- Processed data transforming gene links into force network data.
Full-stack JavaScript Developer
Trinity Mobile Networks
- Optimized Google Maps to host and update 10,000+ markers in real time.
- Developed several AngularJS features on the main portal.
- Implemented portal unit testing with Mocha and Chai.
- Implemented an ES6 transpiler for the AngularJS portal.
Ionic Developer
Visio Green (via Toptal)
- Developed the application from scratch, choosing to implement ES6 into an Ionic project that come out to worked really well and take advantage of it.
- Developed the project and its architecture from scratch.
- Turned wireframes into screens.
- Optimized information management across the platform.
Senior Front-end Developer
Lystnr.com (via Toptal)
- Developed a pixel-perfect landing page.
- Added new features to the AngularJS app, turning links into editable fields.
- Added new endpoints to the AngularJS app.
- Created new form templating.
Front-end Developer
Pampered Chef (via Toptal)
- Developed several apps in Angular 2.
- Improved templates for the client's main site in HTML5 and CSS.
Full-stack Developer
Heal (via Toptal)
- Developed the client's portal web app from scratch.
- Set the architecture for the new AngularJS site.
- Turned wireframes into a working site.
- Helped with some UI/UX decisions.
Full-stack Developer
Fapl (via Toptal)
- Worked along the CEO developing the main site and mobile app.
- Helped with the back-end implementation, suggesting and researching better and more secure methods.
- Implemented a secure file upload with Amazon S3.
- Developed several sections of the mobile and web app, which were both based in AngularJS.
Web Developer
Monsoon
- Used new frameworks like AngularJS and Ember.js.
- Specialized in CSS and responsive design.
Full-stack JavaScript Developer
Kidozen
- Worked with a Node.js back end for managing connectors and on the front-end side with a custom JavaScript framework. Got the opportunity to contribute to an ACE editor while working on Kidozen.
JavaScript Developer
Motorola
- Worked with a custom framework.
- Had a great experience working in an Agile environment.
- Led the team and interviewed new developers.
Mobile Developer
Blanco Martin & Assoc.
- Designed and developed a number of Android and iOS mobile apps using HTML5.
- Implemented a RESTful API during development of the apps.
- Made UI/UX design decisions.
UI Developer
Globant
- Developed a one-page JavaScript application for Intel AppUp using several different frameworks, including Ember.js, YUI, Backbone.js, and Node.js for the back end.
- Created a travel web page for AmEx using JavaScript, HTML5, and Ruby. The site included a vacation planning page, which gives users the option of booking hotels, flights, cars, and various travel packages.
- Developed SKL, a flash cards game for Facebook. Wrote the interface and data management aspects using ActionScript 3.
ActionScript 3 Developer
MindSmack
- Developed a number of highly interactive sites and games using Flash, including RPG, action, and graphic adventure games.
- Created an entire ActionScript 3 framework for isometric games.
- Designed and coded several websites using HTML, CSS, and JavaScript.
Web Developer
TecnoImagen
- Built dynamic websites from scratch using Flash and XML for several companies.
Experience
Water Collection Systems Data Collection and Analysis
StayAfloat
Agora
https://agora.ampadportal.org/genesIt was a MEAN stack app. I helped develop the app in general and completely designed and deployed the network widget, which required distilling a complex set of relationships into an understandable view of a candidate ad target.
Heal | Front-end Engineer
https://patient.heal.com/Fapl, Co.
Working closely with the CEO and the founding engineers, I contributed to defining the technical architecture and user experience for both the web and mobile applications. I played a key role in transforming product concepts and Figma designs into functional, responsive user interfaces built with Angular.js, Ionic, and Bootstrap, ensuring design fidelity and optimal usability across devices.
Pampered Chef
I also helped on templates to improve the main site.
Lystnr
Fareness
Swyp Card
Intel AppUp
AmEx Travel
https://travel.americanexpress.com/homeTo-do App | Backbone and SlimPHP Framework
MindSmack Madness
Polaner
Ortega
Portal Vecino
Education
Bachelor's Degree in Multimedia Design
La Metro - Cordoba, Argentina
Skills
Libraries/APIs
jQuery, RxJS, Google Maps, Highcharts, Google Maps API, Node.js, D3.js, Google Maps JavaScript API 3, Google Maps API (GeoJSON), REST APIs, DC.js, Handlebars, JavaScript API for Chrome, React, Stripe, Stripe API, NgRx, NgRx/store
Tools
Git, Slack, Gulp, Bitbucket, GitHub, NPM, Confluence, Webpack, Sublime Text, Angular CLI, Atom, Grunt, Mercurial, GitHub CLI, Microsoft Access, Visual Studio, Jira, Adobe Photoshop, Adobe Illustrator, Sketch, AWS CodeCommit, Pixelmator, Figma, GIS
Languages
SCSS, CSS, Sass, CSS3, JavaScript, HTML5, HTML, ECMAScript (ES6), TypeScript, Less, ActionScript 3
Frameworks
Bootstrap 3+, Bootstrap 3, Bootstrap, AngularJS, Angular, Angular Material, Material UI, JavaScript MVC, Ionic, Express.js, Next.js, Tailwind CSS, Cypress, Svelte
Paradigms
Agile Software Development, Responsive, Object-oriented Programming (OOP), BEM, Event-driven Programming, Unit Testing, Search Engine Optimization (SEO), Asynchronous Programming, Design Patterns, Mobile Development, Prototype-based OOP, REST
Platforms
MacOS, Firebase, Azure
Storage
JSON, Amazon S3 (AWS S3), MongoDB, MySQL, SlimPHP
Industry Expertise
Healthcare, Photography
Other
Angular Bootstrap, Vine API, Mega, Front-end, Front-end Development, Large-scale Projects, RESTFul APIs, Web Development, Chrome DevTools, Cordova, Angular Component Architecture, Full-stack, Google Maps Styling, APIs, API Integration, Data Visualization, Material Design, Responsive Design, Front-end Architecture, Responsive UI, HIPAA, Real-time Data, Minimum Viable Product (MVP), Artificial Intelligence (AI), CI/CD Pipelines, PSD to HTML, Yam, Illustration, Web UI, Bootstrap 4, Visualization, Dashboards, Community Management, AI Pipeline, Marketplaces, AI-generated Code, GitHub Actions
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