John is available for hire
Hire JohnJohn Mulholland
Verified Expert in Engineering
Software Engineer and Developer
American Fork, UT, United States
Toptal member since December 22, 2025
Bio
John is a senior Android engineer with 20+ years of experience in software development. He specializes in Android using Kotlin and Jetpack Compose, with additional expertise in React Native and back-end integrations. John uses AI-assisted coding thoughtfully to improve quality and velocity, and excels at clarifying complex codebases and delivering maintainable, production-ready solutions.
Portfolio
Varo
Android, Kotlin, Jetpack Compose, React Native, JavaScript, TypeScript
Gabb
Android, Kotlin, Jetpack Compose
Toast
Android, Kotlin, Legacy Code
Experience
- Software Engineering - 20 years
- Android - 13 years
- Kotlin - 6 years
- REST APIs - 5 years
- Jetpack Compose - 3 years
- React Native - 1 year
- AI-augmented Software Engineering (AIASE) - 1 year
- GraphQL - 1 year
Preferred Environment
Android, Kotlin
The most amazing...
...project I've worked on as a software engineer involved work to grow food on a space station.
Work Experience
Staff Android Engineer
2023 - 2025
Varo
- Implemented complex React Native modules for maps and Google's wallet.
- Helped kick off a major bug hunt after finding some discrepancies with analytics.
- Mentored and assisted other engineers during major company changes.
- Used Copilot to assist in building features and tests.
Technologies: Android, Kotlin, Jetpack Compose, React Native, JavaScript, TypeScript
Senior Android Engineer
2023 - 2023
Gabb
- Created some cohesion with other Android engineers by creating a Slack channel and a biweekly Android meeting.
- Solved many problems with Knox Manage for an upcoming phone release.
- Prototyped app blocking on Android phones to allow only certain apps to be used at certain times.
Technologies: Android, Kotlin, Jetpack Compose
Staff Android Engineer
2022 - 2022
Toast
- Led a rush project for a critical customer successfully.
- Reinvigorated the staff engineer discussion group throughout the company.
- Participated on both sides of the mentorship program.
Technologies: Android, Kotlin, Legacy Code
Senior Android Engineer
2020 - 2022
ustwo
- Made progress within the team despite vast complexity, constantly changing processes, and a changing international team.
- Managed to complete several tasks by the end of the first sprint, at which the client was both pleased and very surprised.
- Achieved great client satisfaction and, as a result, the client extended the contract five times.
Technologies: Android, Kotlin, Wear OS
Senior Android Engineer
2020 - 2020
Robert Half International
- Learned how to use multiple bleeding-edge technologies such as Flow and Store.
- Helped update the JustServe app using Navigation, Room, Flow, and Store.
- Converted code to use Android Jetpack components, including Navigation, Room, and MVVM.
- Added features and upgraded legacy code on the Seminary and Institute app using Navigation, Room, Flow, and Store.
- Drove the Seminary and Institute projects to be completed despite numerous challenges.
Technologies: Android, Kotlin
Senior Android Engineer
2019 - 2020
Thrive Global
- Kept great code quality despite pressure to rush projects.
- Converted code to 100% Kotlin, using Android Jetpack components such as Navigation, Room, and MVVM.
- Debugged a very complicated network issue with IPv6.
Technologies: Android, Kotlin
Senior Android Engineer
2014 - 2019
Ancestry
- Helped manage the growth of the mobile team as it expanded. Helped adjust to new processes while producing new features and maintaining existing code.
- Led Android development initiatives to improve code quality and release efficiency through SOLID practices and refactoring.
- Mentored engineers and drove major refactoring initiatives to update the codebase.
Technologies: Android, Kotlin, Legacy Code
Experience
Fitness App for a Smartwatch
I created and developed a project for an exercise app on a smartwatch, utilizing cutting-edge hardware and software. The solution uses various watch sensors to track the user throughout their workouts, including calculations performed locally.
Ancestry Maps and Next Generation Hints
While at Ancestry, I led teams in adding maps to visualize where your family history occurred. I was also able to lead another project, which showed a potential match for a previous generation ancestor based on internal data from other trees.
Refactoring Large Apps
I have taken on large codebases and vastly improved them. While at RSG, I came up with an algorithm to measure code risk and complexity and then refactor, with tests, replacing massive amounts of legacy code and fixing bugs. At Ancestry, we broke up the existing code into modules, which allowed us to exceed the then 999-file limit in our Git repository.
Education
2004 - 2005
Master's Degree in Electrical Engineering
Utah State University - Logan, UT, USA
Skills
Libraries/APIs
REST APIs
Languages
Kotlin, GraphQL, JavaScript, TypeScript
Paradigms
Agile, Code Refactoring
Platforms
Android
Frameworks
React Native, Android SDK
Other
Software Engineering, Jetpack Compose, AI-augmented Software Engineering (AIASE), Wear OS, Legacy Code, Electrical Engineering, RESTFul APIs
Collaboration That Works
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
1
Share your needs
Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2
Choose your talent
Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3
Start your risk-free talent trial
Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.
Top talent is in high demand.
Start hiring