Publication
Why Top Software Engineers Work Freelance
https://www.toptal.com/insights/agile-talent/why-top-software-engineers-work-freelance
Elijah is available for hire
Hire ElijahElijah Windsor
Verified Expert in Engineering
React Native Developer
Kailua, HI, United States
Toptal member since February 10, 2014
Bio
Elijah builds and rescues consumer mobile apps in React Native — the kind people open every day, where reliability at scale is the business model. Apps he's built or taken over have passed 5+ million downloads and hold 4.5–4.9 stars across 237,000+ ratings. Elijah built KashKick's app, which paid out $18.9 million to users in 2025, and rearchitected a stalled Imagine Golf build to 4.9 stars. Teams usually bring him in when a production app is in trouble.
Portfolio
Refined Edge Solutions
Firebase, React Native, PostgreSQL, Ruby on Rails (RoR), Ruby, MongoDB...
Next Epic
React Native, Expo, TypeScript, GraphQL, Hasura, React, Figma, REST APIs...
Alea Diagnostics
React Native, GraphQL, Node.js, iOS, React, Figma, REST APIs, Front-end, Axios...
Experience
- JavaScript - 18 years
- Objective-C - 13 years
- iOS - 12 years
- React - 11 years
- React Native - 11 years
- Redux - 5 years
- ECMAScript (ES6) - 4 years
- Firebase - 4 years
Preferred Environment
Xcode, GitHub, Atom, Front-end
The most amazing...
...thing I've helped develop is a mobile SDK that works with iOS, Android, and React Native that allows deployment of native user-interface on the web.
Work Experience
Developer | CEO
2015 - PRESENT
Refined Edge Solutions
- Built and still lead KashKick's React Native app — a rewards platform with over 5 million installs at 4.7 stars across 226,000 ratings. Built the partner SDK integrations, offering attribution, reward ledgers, and payout flows that paid users $18.9 million in 2025.
- Took over Imagine Golf's stalled iOS build from an outside firm and rearchitected it for usability and scale, then maintained it since — paid content library, tiered subscription billing. It holds 4.9 stars on iOS and 4.8 on Android.
- Joined a large team at Integrated Digital Solutions to help them develop a cross-platform streaming app for AT&T using React Native.
- Built a map-based social network from the ground up using React Native, MapBox, Firebase, Heroku with Node.js, and MongoDB. It uses real-time geolocation to constantly update users' locations, letting them know what is happening around them.
- Led a cross-continent team of Toptal developers in rebuilding an iOS social networking app in React Native using Redux for storing state.
- Helped a well-funded startup convert a website into a truly native React Native app for iOS and Android. I worked with their existing Node.js and MongoDB stack, as well as third-party libraries, to create a better experience on mobile.
- Architected an international company's React web application to be isomorphic to ensure SEO compatibility, using React Router and Express, and also implemented the Redux store.
- Developed a workout editing tool for iPhone apps for a San Francisco-based startup using React, Bootstrap, Ruby on Rails, and Node.js.
- Supported the development of an enterprise iPad quiz app used in corporations for training using PhoneGap, JavaScript, CSS, and Xcode.
- Developed a cross-platform React Native app for iOS and Android for demonstration purposes that queries APIs with GraphQL for display.
Technologies: Firebase, React Native, PostgreSQL, Ruby on Rails (RoR), Ruby, MongoDB, InfluxDB, Objective-C, Bootstrap, PHP, PhoneGap, Titanium, Node.js, JavaScript, Express.js, Flux, Redux, React, Mobile Development, TypeScript, Gatsby, Figma, REST APIs, Front-end, Axios, React Navigation, Android, Python, Trading, Trading Bots, Claude, Claude Code, Full-stack, Large Language Models (LLMs), Claude API, NoSQL, Google Play Store
Senior React Native Engineer
2022 - 2022
Next Epic
- Developed a custom dynamic search UI for Myodetox using React Native Reanimated that shows a touch feedback response when the user answers questions tailored to their interests.
- Built an article viewer that takes raw HTML and renders it natively in a pop-up modal while tracking which items the user has viewed and ensuring it displays a fresh one every day.
- Implemented GraphQL and REST APIs for secure interaction with the back end and conducted thorough testing in both Expo Go and Expo Bare Workflow.
- Worked on a video viewer similar to Instagram Stories that allows users to navigate back and forth through the stories tailored to the client.
Technologies: React Native, Expo, TypeScript, GraphQL, Hasura, React, Figma, REST APIs, Front-end, Axios, React Navigation, Full-stack, Google Play Store
Lead React Native Developer
2022 - 2022
Alea Diagnostics
- Refactored some common pain points associated with React Native development into existing code developed at Harvard.
- Created the Timeline feature within the app, enabling infinite horizontal scrolling functionality, where each day showcases vertical scrolling items representing a child's growth progress.
- Fixed memory leaks and performance issues found in various parts of the app, most notably displaying large portions of data retrieved via GraphQL.
- Managed the development flow by creating separate environments for staging and production on the front-end, ensuring the QA sequence went according to plan.
- Reviewed front and back-end code from other team members before deploying new versions.
Technologies: React Native, GraphQL, Node.js, iOS, React, Figma, REST APIs, Front-end, Axios, React Navigation, Full-stack, Google Play Store
Senior React Native Developer
2021 - 2022
GrowthDay
- Helped develop the Challenges section of the GrowthDay app, implementing and iterating UI designs and ensuring UX engagement was on point.
- Collaborated with the back-end team to ensure the API calls were appropriately integrated and worked with the QA team on any discovered issues.
- Adapted existing iOS and Android native libraries, which were not initially compatible with React Native, to make them usable within our app.
Technologies: React Native, JavaScript, TypeScript, Objective-C, React, REST APIs, Front-end, Axios, React Navigation, Full-stack
Senior React Native Developer
2020 - 2021
Integrated Digital Solutions
- Optimized the performance of the React Native application across multiple devices, including iOS, Android, FireTV, and AppleTV platforms.
- Refactored and cleaned up code to ensure maximum performance on mobile and TV devices.
- Developed native modules to integrate fixes for both iOS and Android applications.
Technologies: React Native, JavaScript, Objective-C, Java, React, TypeScript, REST APIs, Front-end, React Navigation
Senior Software Developer
2014 - 2015
GAIN Fitness
- Created chat functionality in a trainer enterprise app using Objective-C, Ruby on Rails, PostgreSQL, and APNS.
- Created an in-house Apple Watch extension to allow users to monitor progress of their workouts and switch exercises.
- Created a script to dig through and piece together over half a million user records stored between CouchDB and PostgreSQL.
- Supported architecture of back-end and REST API creation using Ruby on Rails and PostgreSQL.
- Created an admin tool for sending SMS messages with links to install enterprise iOS apps to trainers using Twilio, Ruby on Rails, and PostgreSQL.
Technologies: Redux, Core Data, CSS, HTML, Apple Watch, Objective-C, MongoDB, PostgreSQL, Ruby on Rails (RoR), Ruby, JavaScript, Flux, React, Mobile Development, Amazon Web Services (AWS), REST APIs, Front-end
Director of Engineering
2013 - 2014
Appstem Media, LLC
- Created an iPhone app allowing real-time communication using chat, image/recording uploads, in-app phone calls, and text messaging using Objective-C, ObjectiveDDP, Twilio SDK, Meteor, and Node.js.
- Built a customizable voicemail system for doctors using Twilio, Meteor, Node.js, and MongoDB.
- Created an in-house iPhone app for real-time interactivity for browsing folders and viewing files with Objective-C, Socket.io, Node.js, and Box API.
- Created an iPad app for a Napa Valley winery to track inventory using Objective-C and Visual C#.
- Added features to a cross-platform enterprise real-estate app using Titanium for iOS and Android.
Technologies: MongoDB, Titanium, Meteor, Node.js, Objective-C, Mobile Development, REST APIs, Front-end
Developer and Owner
2007 - 2014
Smooth Edge Design
- Created an iPhone app for taking photos of your dog that was mentioned by Jay Leno and featured in news stories across the country in 2009 using Objective-C.
- Supported customization of chocolate website osCommerce shopping cart using PHP and MySQL.
- Supported a manuscript editing website by adding a custom shopping cart using Ruby on Rails and JavaScript.
- Created a friend finding iPhone app that was the catalyst to Flywheel Software using Objective-C, Ruby on Rails, and MySQL.
- Created a custom music player for the web using Flash, ActionScript, PHP, and MySQL.
- Created several websites for non-profit organizations using HTML, CSS, PHP, MySQL, and JavaScript.
- Created a custom slideshow that cycled through images asynchronously using Flash, ActionScript, PHP, and MySQL.
Technologies: Objective-C, Ruby on Rails (RoR), Ruby, CSS, HTML, jQuery, JavaScript, Flash ActionScript, Flash, PHP, Mobile Development, REST APIs, Front-end
Contract Developer
2012 - 2013
Purl, Inc.
- Created a user-interactive search tool in a native iPhone app for finding content online and pinning it to a geolocation using iOS Geolocation, Titanium, JavaScript, Node.js, and MongoDB.
- Developed a customized search algorithm for finding relevant information about the current location of users with Bing API, Foursquare API, iOS Geolocation, and JavaScript/Node.js.
- Created a back-end API for posting websites to a specific geolocation as well as geolocation-based lookup using iOS Geolocation, JavaScript, Node.js, and MongoDB.
- Created an admin panel for managing existing postings and creating admin-based postings using HTML5, JavaScript, Node.js and MongoDB.
- Built an iPhone app for hotel guests to find nearby attractions using PhoneGap, JavaScript, Node.js, and MongoDB.
Technologies: MongoDB, Node.js, PhoneGap, Titanium, JavaScript, Objective-C, Mobile Development, REST APIs, Front-end
Founding Developer
2009 - 2011
Flywheel Software, Inc.
- Created an iPhone app for drivers and passengers to see each other on maps in real time using Objective-C and Erlang.
- Developed a back end for socket-based connectivity using Erlang.
- Built a XMPP custom-protocol for hailing passenger to driver using Erlang and ejabberd.
- Created a dispatch web app to allow dispatchers to assign pickup locations to drivers with a mobile app using HTML5, JavaScript, Strophe, and Erlang.
- Developed a cross-browser compatible solution for recording sound and delivering to drivers via a mobile app using JavaScript, Flex, ActionScript 3.0, and Erlang.
Technologies: XMPP, JavaScript, Erlang, Objective-C, Mobile Development, REST APIs, Front-end
Experience
Howl - Find Friends & Nightlife
Using React Native and Firebase and Twilio, I assisted in optimizing this app and adding brand-new features, utilizing both JavaScript on the client-side and on the Node.js/Firebase functions side. I was able to help bring it to a state that is stable and secure in production.
Social Network App Built in React Native
I led a small team in building an iOS app in roughly 1 month from scratch using React Native. It uses Redux to store states and has custom modules built in Objective-C to perform operations triggered by JavaScript, including photo compression and video uploading.
Bluewolf Website
http://www.bluewolf.com/Using React.js, I turned this into an Isomorphic web app, using Redux and Express. It will render server-side so there's data immediately available for the user (and good for search engines) as well as client-side so the user gets instant feedback and can browse more effectively.
Dabawallah | Dinner Made Easy
Using React.js and Redux, I developed a dashboard web app which looks and feels a lot like a native desktop app. You can select restaurants that are in the area and create meal playlists that can be delivered to you the next week.
Meridix Real-time Websockets
http://www.meridix.com/Using Node.js, Socket.IO, PHP, and Redis, I built a scalable WebSocket app that allows broadcasters to send viewers updated scores and stats during games they're watching.
Flywheel Software, Inc.
http://www.flywheel.com/This company initially consisting of just the CEO and myself. Flywheel Software has raised over $30 million.
Secure User Authentication | Enterprise iPad Application
I developed a critical component of an enterprise iPad application, LoginViewController.m. This module is specifically designed to facilitate secure user authentication.
The application is configured to operate exclusively on designated iPads, identified by their unique MAC addresses. The initial step in the authentication process involves verifying the device's MAC address. Upon successfully validating the MAC address, the system authenticates the user credentials. The user is prompted to input their username and password, which the system verifies. This two-tiered security protocol ensures robust protection against unauthorized access.
The application is configured to operate exclusively on designated iPads, identified by their unique MAC addresses. The initial step in the authentication process involves verifying the device's MAC address. Upon successfully validating the MAC address, the system authenticates the user credentials. The user is prompted to input their username and password, which the system verifies. This two-tiered security protocol ensures robust protection against unauthorized access.
CosRank - CosPlay iPhone App
I built this photo sharing social network in Objective-C with Node.js on the back-end.
Education
2001 - 2005
Bachelor's Degree in Computer Science
Purdue University - West Lafayette, IN, USA
Skills
Libraries/APIs
Redux-Saga, React Redux, Lodash, React, Parse SDK, Node.js, jQuery, Underscore.js, Socket.IO, ObjectiveDDP, REST APIs, React Navigation, Claude API, X (formerly Twitter) SDK, iOS Extensions, Facebook iOS SDK, Handlebars, Foursquare API, Facebook Open Graph API
Tools
Redux Thunk, Appcelerator Titanium, Xcode, Babel, iOS Simulator, GitHub, SourceTree, Chrome Developer Tools, Figma, Claude Code, NGINX, Node Inspector, iOS Instruments, Sublime Text 2, Claude, Atom, Flash, Adobe Photoshop, Expo
Languages
PHP, HTML, CSS, Objective-C, ECMAScript (ES6), JavaScript, Go, TypeScript, Java, SQL, Ruby, Swift, Python, Erlang, Flash ActionScript, GraphQL
Frameworks
Redux, React Native, Ruby on Rails (RoR), Bootstrap 3, Flux, AFNetworking, MapKit, Core Location, UIKit, ZURB Foundation, Titanium, Android SDK, Express.js, PhoneGap, CFNetwork, Bootstrap, Core Data, Kendo UI
Paradigms
Object-oriented Programming (OOP), Asynchronous Programming, Mobile Development, Model View ViewModel (MVVM), Test-driven Development (TDD), Agile Software Development, Key-Value Observing (KVO), Event-driven Programming, Data-driven Programming
Platforms
Firebase, iOS, Meteor, Android, Mapbox, Amazon EC2, AWS Elastic Beanstalk, Ubuntu, Apple Watch, Amazon Web Services (AWS)
Storage
NoSQL, Cloud Firestore, SQLite, PostgreSQL, MySQL, MongoDB, CouchDB, InfluxDB, Hasura
Other
Sagas, Ajax, Software Architecture, Front-end Development, Front-end, Axios, Mobile Apps, Full-stack, Google Play Store, Cordova, WebSockets, Gatsby, Trading, Large Language Models (LLMs), XMPP, Software Development, Computer Science, Leadership, User Authentication, Trading Bots
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