Jeff Johnson, Developer in Denver, CO, United States
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Jeff Johnson

Verified Expert  in Engineering

Android Developer

Denver, CO, United States
Toptal Member Since
December 5, 2020

Jeff has five years of varied Android experience. It is both his specialty and passion. He has worked with Fortune 100 companies to implement and refine their mobile app vision to greenfield R&D work with a startup on mobile SDKs to support computer vision. Jeff will bring your Android app to life. Equally comfortable making architectural improvements and fixing bugs as plotting out and building something new, Jeff would love to help you with all things Android.



Preferred Environment

Firebase, Cloud Firestore, Android

The most amazing...

...project I've worked on is a mobile SDK, created from scratch, to support a machine learning, computer vision offering.

Work Experience

Senior Android Developer

2017 - PRESENT
  • Maintained 99+% crash-free user rate for an Android application with > 10,000 monthly active users, while adding countless new features.
  • Built a greenfield Android application using the Firebase suite of tools to support an image recognition offering.
  • Built scalable Android libraries to support image recognition integration into other applications.
  • Rearchitected an important user profile persistence layer of the application, which previously caused crash-free user rates to dip to 93%. After rearchitecting, the crash-free user rate returned to 99%.
Technologies: Cloud Firestore, Firebase, SQLite, Android

Android Engineer

2015 - 2016
Solstice Mobile
  • Reduced the average duration of an important, multi-threaded, chained network call in a client’s app by 75% by retooling the handling of individual network calls.
  • Integrated external libraries and RESTful APIs into Android apps.
  • Improved screen lag by 95% on the map screen of a client’s app by implementing a bi-directional HashMap to circumvent slow internal look-up functions.
Technologies: OkHttp, SQLite, Android

Computer Vision Support SDK

An Android SDK that allows users to capture photos and receive immediate feedback on the quality of those photos using frameworks such as MLKit, OpenCV, and TensorFlow Lite, and then submit those photos to a back end. The SDK can also receive results from that same back end and display the annotated photos and other useful aggregate data to the user and provide useful feedback on what they submitted.

The SDK works entirely offline, data syncs in real-time, and is easily integrated into any Android app.


Kotlin, Java




Android, Firebase


OkHttp, Data Structures, Algorithms, Coroutines


Model View Viewmodel (MVVM)


Cloud Firestore, SQLite

2011 - 2015

Bachelor's Degree in Physics, Computer Science, Mathematics

Occidental College - Los Angeles, CA