Gabor is available for hire
Hire GaborGabor Biro
Verified Expert in Engineering
Software Developer
Lisbon, Portugal
Toptal member since August 4, 2021
Bio
Gabor is a senior/lead Android engineer with 10+ years of Android experience and 15+ years in software. He's worked at Facebook, Deliveroo, Goldman Sachs, and startups, and most recently built and owned Somnology's Android app largely from scratch. Strong in Kotlin, Jetpack Compose, Coroutines/Flow, architecture, BLE, health-data integrations, automated testing, and CI/CD, Gabor is comfortable owning products end to end and working directly with back-end, iOS, QA, and product teams.
Portfolio
Somnology, Inc.
Kotlin, Jetpack Compose, Android, REST, Bluetooth, Google Play API...
Goldman Sachs
Android, Kotlin, Android Studio, Agile, Jetpack Compose, Android Jetpack...
Ontraport
Android, Kotlin, Agile, Clubhouse, Zeplin, APIs, REST, Retrofit 2, KOIN...
Experience
- Java - 10 years
- Android - 10 years
- Software Engineering - 10 years
- Git - 9 years
- Android Studio - 6 years
- Agile - 5 years
- Kotlin - 4 years
- Firebase - 3 years
Preferred Environment
Windows 10, Android Studio, IntelliJ IDEA, Visual Studio Code (VS Code), Notepad++, Notion, TortoiseGit, SourceTree, Google Chrome
The most amazing...
...thing I've done is release a bug fix that affected billions of Facebook users.
Work Experience
Android Developer
2024 - PRESENT
Somnology, Inc.
- Developed an Android application largely from scratch as the primary Android engineer, owning its architecture, technical direction, delivery, testing, and releases.
- Built connected-ring functionality covering BLE discovery, recording control, live biometrics, sleep-data upload, firmware updates, and device-state recovery.
- Integrated Samsung Health sleep data with back-end services through scheduled and user-triggered synchronization, duplicate detection, and diagnostic reporting.
- Designed mobile/back-end API contracts and cross-platform behavior with back-end and iOS engineers, including version compatibility, notifications, and deep linking.
- Built automated Android testing and release infrastructure, including Compose UI tests, dependency injection test support, CI pipelines, and production signing.
- Improved the reliability of background health-data synchronization using WorkManager, handling intermittent connectivity, retries, authentication, and partial failures.
- Designed the Android push-notification architecture around FCM, defining typed payloads, navigation behavior, and handling across foreground and background states.
- Drove product and technical design beyond Android, translating clinical and business workflows into requirements for booking, onboarding, payments, and patient care.
- Designed a direct-to-consumer strategy that reused existing clinical infrastructure for self-service onboarding, appointment booking, payment, and sleep diagnostics.
- Investigated production failures across mobile, back-end, and connected-device boundaries, diagnosing intermittent networking, authentication, and device-state issues.
Technologies: Kotlin, Jetpack Compose, Android, REST, Bluetooth, Google Play API, Bluetooth Low Energy (BLE), Coroutines, Flow, GitHub, GitHub Actions, GitLab CI/CD, CI/CD Pipelines, UI Testing, Automated UI Testing, Android Development
Senior Android Developer
2021 - 2024
Goldman Sachs
- Implemented features based on design specifications, including enabling users to scan and deposit paychecks in the app and integrating customer support chat.
- Led investigations for major incidents and documented post-mortems. Provided on-call support and release monitoring.
- Integrated 3rd-party software/API and collaborated with vendors.
- Groomed tickets and conducted code reviews for other team members' contributions.
- Contributed to a state-of-the-art codebase, using various tools, technologies, and paradigms while maintaining code quality via a comprehensive, multilayered testing strategy.
- Conducted interviews and facilitated the onboarding process for new team members.
Technologies: Android, Kotlin, Android Studio, Agile, Jetpack Compose, Android Jetpack, RxJava, Reactive Programming, RxAndroid, GitHub, GitLab, GitLab CI/CD, CI/CD Pipelines, Model View ViewModel (MVVM), Model View Intent (MVI), Testing, UI Testing, Integration Testing, E2E Testing, Unit Testing, JUnit, Mockito, Dagger 2, KOIN, Hilt, Mobile Architecture, Android Development
Freelance Android Tech Lead
2020 - 2021
Ontraport
- Built the app that allows users to view and manage their contacts, deals, tasks, notes, fully custom objects as well as manage relationships between them, like assign tasks to contacts, and manage deals associated with companies.
- Designed, implemented, and maintained the architecture, set the direction for the rest of the team and supported the project post-release. Worked as part of a team of around three people.
- Worked with a massively complex API that was not intended to be used by mobile clients, but we pulled it off and created something that worked reliably and smoothly, and the client was happy. Visit https://play.google.com/store/apps/details?id=com.ontraport.android to see the app.
Technologies: Android, Kotlin, Agile, Clubhouse, Zeplin, APIs, REST, Retrofit 2, KOIN, Model View ViewModel (MVVM), Android Jetpack, Coroutines, RoomDB, Firebase, Coil, Zendesk API, Android Studio, Slack, TortoiseGit, Mobile, REST APIs, RxJava, Mobile Development, Android Development
Freelance Android Developer
2019 - 2020
Tempcon Instrumentation Ltd
- Designed the app, its architecture and implemented it. It was connected to an industrial hand-held thermometer via BLE Bluetooth and I implemented the BLE client.
- Worked on the app that allowed users to record temperature measurements for things like cooked food or water in a treatment facility and send email reports.
- Created the app that ended up being quite complex, with pre-set measurement profiles.
Technologies: Android, Kotlin, SQLite, Bluetooth Low Energy (LE), Android Studio, Slack, TortoiseGit, Dagger 2, Mobile, REST APIs, Google Cloud, Mobile Development, Minimum Viable Product (MVP), Bluetooth, Android Development
Freelance Android Developer
2019 - 2020
Vemely
- Worked on the Vemely, a social media content creator app, initially built for iOS where users can upload videos and the app embeds subtitles into them.
- Built the Android app and release it to Play Store. Check out https://play.google.com/store/apps/details?id=com.luminixmarketing.vemely to see the app.
- Implemented video editing with FFmpeg, so users can have multiple ongoing projects, view their status, edit them and publish them to various social media platforms such as Instagram, YouTube, and Twitter directly from the app.
Technologies: Android, Kotlin, Firebase, SQLite, Dagger 2, Video Processing, FFmpeg, Android Studio, Slack, TortoiseGit, SourceTree, Mobile, REST APIs, Mobile Development, Android Development
Android Developer
2017 - 2019
Deliveroo
- Acted as an Android developer and was responsible for the app used by Deliveroo riders to navigate their way from the restaurant to the consumer as well as tracking their payments and scheduling their work.
- Served as a part of the Rider Care team and was responsible for developing tools for riders.
- Developed features enabling riders to book work ahead of time for fair access and to book time off for peace of mind. The app Deliveroo Rider is available on Google Play.
Technologies: Android, Dagger 2, Retrofit 2, Google Maps, Agile, Kotlin, RxJava 2, SQLite, Android Studio, Slack, TortoiseGit, Mobile, REST APIs, RxJava, Mobile Development, Mobile Architecture, Android Development
Freelance Android Developer
2018 - 2018
AddyCar
- Built an Android app that allowed users to earn money by serving adverts on their cars.
- Worked on the app allowed users to register their car, receive campaigns and apply to them.
- Implemented tracking GPS location feature while driving in order to ensure fair compensation. Visit https://play.google.com/store/apps/details?id=com.addycar.driverapp to see the app.
Technologies: Google Maps, Android, RxJava 2, MongoDB, SQLite, Dagger 2, Retrofit 2, Kotlin, Mobile GPS, Location Tracking, Android Studio, Slack, TortoiseGit, A-GPS, Mobile, REST APIs, Mobile Development, Minimum Viable Product (MVP), Android Development
Senior Android Developer
2016 - 2016
Hailo
- Was responsible for the application used by customers to hail a taxi.
- Increased the number of user signups by implementing signup with PayPal. I also helped reduce the number of trip cancellations by participating in the respective R&D and experimentation and implementing the winning UI features.
- Helped to migrate passengers to a new app (MyTaxi) after a company merger.
Technologies: Android, Git, Jira, Jenkins, Android Studio, TortoiseGit, Retrofit 2, Mobile, REST APIs, Mobile Development, Android Development
Software Engineer
2015 - 2016
- Increased user interactions and revenue on the Snaptu platform, which is the back end for the Facebook mobile app on feature-phones in emerging countries.
- Shipped several UI/UX improvements for a multi-cultural, performance- and bandwidth-constrained environment of millions of users all across the planet.
- Worked on the Facebook Android application which is the world’s largest Android codebase.
- Worked at Facebook and had the opportunity to familiarize myself with the “Silicon Valley work style” which is a very passionate, independent (bottom-up) way to work while also being very product-oriented and highly international.
Technologies: Android, Java, GraphQL, Android Studio, Mobile, Mobile Development, Android Development
Senior Android Developer
2013 - 2015
Endava
- Served as a part of a large international team, developed, and supported Android applications in Scrum environment.
- Worked on the Telekom Mail app – official email client for Deutsche Telekom, the biggest telecommunication company in Germany.
- Got recognition and I was offered a Germany-based job by a Telekom manager at the end of a project. I didn't take it because it was around that time I got my offer from Facebook and decided to move to the UK instead. Visit see the app. https://play.google.com/store/apps/details?id=de.telekom.mail to.
Technologies: Java, Scrum, Agile, Android, Android Studio, Jira, Mobile, REST APIs, Mobile Development, Android Development
Android Developer
2010 - 2013
Softvision
- Acted as a part of a team and was responsible for numerous projects over the years.
- Worked on the Mr. Number app, the most popular call blocker apps. Visit https://play.google.com/store/apps/details?id=com.mrnumber.blocker for details.
- Collaborated on the Fan TV app - an Android app for TV that allowed users to enjoy movies, music and audiobooks, back when Android TV was a thing.
Technologies: Android, Java, Agile, Android Studio, Jira, Mobile, REST APIs, Mobile Development, Android Development, Android TV
Android and BlackBerry Developer
2008 - 2010
AROBS Software
- Developed and supported Android applications in a Scrum environment.
- Built the OncoEMR app – Android client for the OncoEMR oncology-specific electronic medical records system.
- Created the Hotelzon app – Android and Blackberry client for one of Europe’s biggest hotel booking platforms. Visit https://play.google.com/store/apps/details?id=com.hotelzon to see the app.
Technologies: Java, Scrum, Android, Android Studio, Agile, Mobile, REST APIs, Mobile Development, Android Development
Experience
Bluetooth Companion App for Digital Thermometer
Tempcon Instrumentation Ltd. is a UK-based company that manufactures environmental sensors.
One of their products was a handheld industrial digital thermometer, and they asked me to build a companion app for it. The app connected to the thermometer via BLE Bluetooth, where I implemented the BLE client, allowing users to record temperature measurements for things like cooked food or water in a treatment facility and send email reports.
The app ended up being quite complex, with pre-defined measurement profiles and multiple parallel ongoing measurement projects being supported.
One of their products was a handheld industrial digital thermometer, and they asked me to build a companion app for it. The app connected to the thermometer via BLE Bluetooth, where I implemented the BLE client, allowing users to record temperature measurements for things like cooked food or water in a treatment facility and send email reports.
The app ended up being quite complex, with pre-defined measurement profiles and multiple parallel ongoing measurement projects being supported.
Social Media Content Creator App
Vemely is a social media content creator app initially built for iOS. The user uploads videos, and the app embeds subtitles into them, yet subtitles are transcribed in the back end, not by the app.
My responsibility was to build the Android app and release it to the Play Store. Also, I worked on my own.
I implemented the video editing with FFmpeg. The user can have multiple ongoing projects, view their status, edit them, and publish them directly from the app to various social media platforms, such as Instagram, YouTube, and Twitter.
My responsibility was to build the Android app and release it to the Play Store. Also, I worked on my own.
I implemented the video editing with FFmpeg. The user can have multiple ongoing projects, view their status, edit them, and publish them directly from the app to various social media platforms, such as Instagram, YouTube, and Twitter.
Customer Relationship Management App
https://play.google.com/store/apps/details?id=com.ontraport.androidThe app we built allows users to view and manage their contacts, deals, tasks, notes, fully custom objects as well as manage relationships between them, like assign tasks to contacts, and manage deals associated with companies.
My responsibilities were to design, implement and maintain the architecture, set the direction for the rest of the team and support the project post-release. I worked as part of a team of 2-3.
We had to work with a massively complex API that was not intended to be used by mobile clients, but we pulled it off and created something that worked reliably and smoothly, and the client was happy.
Visit https://play.google.com/store/apps/details?id=com.ontraport.android to see the app.
My responsibilities were to design, implement and maintain the architecture, set the direction for the rest of the team and support the project post-release. I worked as part of a team of 2-3.
We had to work with a massively complex API that was not intended to be used by mobile clients, but we pulled it off and created something that worked reliably and smoothly, and the client was happy.
Visit https://play.google.com/store/apps/details?id=com.ontraport.android to see the app.
Android Developer at Goldman Sachs
https://play.google.com/store/apps/details?id=com.marcus.android&hl=en&gl=USCollaborated with a US investment bank as an Android app developer for two and a half years.
KEY RESPONSIBILITIES
• Implementation of features based on design specifications and integration of 3rd-party software/API and liaison with vendors
• Ticket grooming and code review of team members' contributions
• Participation in discussions regarding platform and architecture upgrades
• On-call support and release monitoring
• Conducting interviews and facilitating the onboarding process for new team members
ACHIEVEMENT HIGHLIGHTS
• Scanning and depositing paychecks in the app
• Customer support chat integration
• Contributing to a state-of-the-art codebase, using a wide variety of tools, technologies, and paradigms while maintaining code quality via a comprehensive, multilayered testing strategy
COLLABORATION AND LEADERSHIP
I continually received good feedback for jumping in and helping in tight situations/deadlines/hotfixes. As the primary investigator, I handled a severe incident, kept stakeholders up to date, sought out the right people in the many back-end teams for information, implemented the fix, prepared post-mortem documentation, and participated in the post-mortem meetings. I also managed on-call rotations.
KEY RESPONSIBILITIES
• Implementation of features based on design specifications and integration of 3rd-party software/API and liaison with vendors
• Ticket grooming and code review of team members' contributions
• Participation in discussions regarding platform and architecture upgrades
• On-call support and release monitoring
• Conducting interviews and facilitating the onboarding process for new team members
ACHIEVEMENT HIGHLIGHTS
• Scanning and depositing paychecks in the app
• Customer support chat integration
• Contributing to a state-of-the-art codebase, using a wide variety of tools, technologies, and paradigms while maintaining code quality via a comprehensive, multilayered testing strategy
COLLABORATION AND LEADERSHIP
I continually received good feedback for jumping in and helping in tight situations/deadlines/hotfixes. As the primary investigator, I handled a severe incident, kept stakeholders up to date, sought out the right people in the many back-end teams for information, implemented the fix, prepared post-mortem documentation, and participated in the post-mortem meetings. I also managed on-call rotations.
Education
2006 - 2009
Bachelor's Degree in Computer Science and Engineering
Technical University of Cluj Napoca - Cluj Napoca, Romania
Certifications
SEPTEMBER 2012 - PRESENT
Oracle Certified Java Associate
Oracle
Skills
Libraries/APIs
REST APIs, RxJava, Retrofit 2, Google Maps, RxJava 2, FFmpeg, Zendesk API, Retrofit, Jetpack Room, Google Play API
Tools
Android Studio, TortoiseGit, IntelliJ IDEA, SourceTree, Git, Slack, Notion, Jira, Jenkins, Clubhouse, Zeplin, Android Jetpack, GitHub, GitLab, GitLab CI/CD, Charles Proxy, Gradle, RxAndroid, Flow
Languages
Java, Kotlin, GraphQL, Java SE 7, Domain-specific Languages (DSLs)
Paradigms
Object-oriented Programming (OOP), Agile, Mobile Development, REST, Model View ViewModel (MVVM), Logic Programming, Parallel Programming, Agile Project Management, Scrum, Clean Architecture, Testing, E2E Testing, Unit Testing, Reactive Programming, Model View Intent (MVI)
Platforms
Android, Mobile, Firebase, Visual Studio Code (VS Code), Google Chrome, Bluetooth Low Energy (LE), Android TV
Frameworks
Dagger 2, KOIN, JUnit, Mockito
Storage
Databases, SQLite, Google Cloud, MongoDB, RoomDB
Other
Software Engineering, Android Development, Data Structures, Algorithms, APIs, Coroutines, A-GPS, Minimum Viable Product (MVP), Jetpack Compose, Mobile Architecture, Windows 10, Digital Systems, Translation, Software Design, Relational Database Design, Video Processing, Coil, Mobile GPS, Location Tracking, GPS, Languages, CI/CD Pipelines, Room, UI Testing, Automated UI Testing, Integration Testing, Pact, Hilt, Bluetooth, Bluetooth Low Energy (BLE), GitHub Actions
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