Greg Ennis, Developer in Atlanta, GA, United States
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Greg Ennis

Verified Expert  in Engineering

Mobile Apps Developer

Atlanta, GA, United States
Toptal Member Since
October 1, 2015

Greg is an expert mobile developer with years of experience building native mobile applications on iOS and Android. He has worked to bring mobile solutions to everyone from small startups to large corporations such as Motorola, Turner Broadcasting, and Cox Communications.


Android, iOS, Swift, Xcode, Visual Studio Code (VS Code), PostgreSQL
Turner Broadcasting
Python, .NET, C#, Gradle, Java, Android, Model View Presenter (MVP)




Preferred Environment

MacOS, Xcode, Visual Studio Code (VS Code)

The most amazing...

...thing I've coded was a complete IrDA stack for communication with a mobile device using infrared transmitters.

Work Experience


2013 - PRESENT
  • Built several native mobile applications from start to finish, including NextGlass, Team Sports HQ, Twiddy, and Likeli.
  • Developed LiveMixtapes to improve performance, reduce memory usage, and increase reliability.
  • Contributed to developing native mobile applications including Collobos, SkySafari, Mac Tools, and Ultimate Photo Widget.
  • Made open-source contributions, including a Mongo Explorer application and BitDiffer system.
Technologies: Android, iOS, Swift, Xcode, Visual Studio Code (VS Code), PostgreSQL

Application Architect

2003 - 2013
Turner Broadcasting
  • Developed a native mobile application called Proximity for tracking video crews and trucks in the field.
  • Built a native mobile application called imMeta for capturing, browsing, and publishing images taken by photographers with Android devices.
  • Created a native mobile tablet application called Lumenbox for viewing and printing branded photos at events.
  • Provided guidance on best practices and shared insight and experience to around 200 developers in the enterprise applications department.
  • Developed an enterprise security framework used by software systems company-wide.
Technologies: Python, .NET, C#, Gradle, Java, Android, Model View Presenter (MVP)

Harley-Davidson Mobile Apps
The Harley-Davidson app offers ride planning, ride recording, extensive mapping, challenges, and social features, as well as connectivity to Harley-Davidson's newer bikes. The app is native to iOS (Swift) and Android (Kotlin).

Collage iOS App
Collage is a social networking app for creating and sharing memes. It's a native iOS app built in Swift. It also contains features for discovering and connecting to other users. It integrates with Snapchat, Facebook, Instagram, and Twitter.

LiveMixtapes Mobile Apps
LiveMixtapes is a highly-rated music streaming and social interaction app with over one million downloads. From the existing codebase, I implemented integration with ExoPlayer and Chromecast, revamped the UI, and modernized the network stack.

Fantasy Sports Lineup Generator
This is a macOS desktop app that allows a user to import data from fantasy sports services and construct a lineup for use in daily fantasy sports games. It combines rich UI to heavily customize parameters for the lineup and intense data processing to produce and export data for use in the fantasy sports services.
I am the sole developer of this app.

NextGlass iOS App

NextGlass is a native iOS application that provides ratings and recommendations for beer and wine based on science. Users can scan labels for beers and view information relating to the beer content, and then rate the beers and view recommendations for other beverages based on the user's profile.

NOTE: The app is no longer available because Untappd acquired the company, now the #1 beer recommendation app on the store.

Food Scanner Open Source App and Back End
This app allows users to scan food item barcodes at the grocery store and reports the list of ingredients that users have indicated they may be sensitive to. It also maintains the history of scans.
The project includes an Android native app, a React Native app for Android and iOS, and a Firebase back end.

Twiddy iOS App
Twiddy is a vacation rental companion app for users to browse information and multimedia about their rental properties. Users can share media, provide feedback to owners, submit maintenance requests, leave feedback, and more directly from the app.

Team Sports HQ Android App

A forthcoming native Android application which allows parents to access sports league information for their kids. Parents can view schedules, participate in discussions, and create and assign tasks from their phone.

Mongo Explorer Open Source Android App
Open source native Android application that is a front-end for Mongo databases. Allows users to connect, browse, and update Mongo database collections from their phone or tablet.

Likeli Mobile Apps

Likeli was a social networking mobile application with an emphasis on real-time events. The app used real-time chat and location information (with consent) to build a heat map of general areas of interest.

Note: The company was acquired and the app is no longer available.
This is the public website for Krispy Kreme. This site runs on ASP.NET 4.5, written in C# and MVC5. The database is SQL Server 2008R2.

Services that provide location and promo data are written using Web API, also with C#.

The site is hosted on IIS7 on Windows Server 2008R2.

Innodroid Applications
Various free and paid applications published on the Play Store, including everything from TV show listings to website monitoring.

MacTools Android App

Native Android application to diagnose vehicle indicator warning lights. I updated and re-skinned this app for use with MacTools branded adapters.

SkySafari Android App
Native Android application for sky charts. I ported this application to Android Studio and was involved in the development of new features.

BitDiffer Open Source .NET Client
An open-source .NET client for examining and reporting on the differences between sets of assemblies. It performs static code analysis, presents results in in-app content, and generates reports. This library is written in C#


Swift, Kotlin, Java, HTML, C#, CSS, JavaScript, Python, Objective-C


Android SDK, UIKit, iOS SDK, .NET, SwiftUI, Core Data, Dagger, ASP.NET


Android Studio, Xcode, Android Jetpack, Git, Gradle, Figma


Mobile Development, Testing, Test-driven Development (TDD), Unit Testing, Model View Controller (MVC), Model View ViewModel (MVVM), Model View Presenter (MVP)


iOS, Mobile, Android, MacOS, Firebase, Visual Studio Code (VS Code), Amazon Web Services (AWS)


Mobile Apps, Mobile Architecture, Mobile App Development, Native Mobile Apps, Location Services, App Store, APIs, Google Play Store, Algorithms, Artificial Intelligence (AI)


Node.js, REST APIs, Facebook SDK, Twitter SDK


SQLite, JSON, PostgreSQL, Databases, MySQL

1993 - 2003

Bachelor's Degree in Computer Science

Williams College - Williamstown, MA

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