Gabriel Gircenko

Yahoo Fantasy Sports is a fantasy sports app delivered in three months. I was in charge of updating features in the Daily Fantasy part of the app while also updating the code from Java to Kotlin and various architectural patterns to MVVM with RxJava. Also, I built guides for the refactoring for other developers to follow.
• Built my tasks according to product directions.
• Used Agile and Kanban with daily scrum meetings.
• Helped update different developer guides and Jira ticket templates and helped optimize processes inside the team.

I developed two premium content-streaming Android applications and their libraries, and my most significant contribution was making the UI code more robust. Until then, there had been more than two bug fixes per week on the UI. After that, we changed the UI only if the specifications changed.

Technologies: Android, TDD, Java, Mockito, PowerMockito

Kotlin and Java are two powerful general-purpose languages popular for Android and beyond. I wrote a blog post where I discussed their top features and differences, then focused on how to smoothly transition between the two.

I participated in the five-people team that Toptal Projects provided for the client, including one senior and junior delivery manager, project manager, and UX/UI designer. I communicated daily with two product owners, one DevOps, and two technical support persons, leading another Android senior engineer.

• I acted as a go-to tech person for this project, performing as an Android architect/lead engineer.
• Took responsibility for research and development and took critical project risks. Researched the market and watched by requirements of the client.
• Set up epics and stories for the MVP in collaboration with the team
• Built a roadmap for delivery.
• Wrote the setup guide for the app to work correctly in the Kiosk mode on the smartwatch.
• Built native calls functionality with custom UI (not VoIP).
• Helped hire a great addition to our Toptal Projects team—a senior Android engineer—who complemented my skills perfectly.

I was in charge of implementing a screen reader accessibility feature from scratch. Working there was one of my best work experiences.

Successfully finished adding the accessibility feature to every screen.

Most of my work on this project consisted of updating the UI and implementing Android Wear API for an urgent release of the podcast application. This was my first Kanban project, made in Android Studio, and hosted on GitHub.

Technologies: Android, Android Wear

A tool for automating the job application process.

I hired two sales representatives through an online freelance agency to help me apply for different positions and gradually automate the process.

We had meetings every day to go through the updates. I introduced advanced and complex usage of Google Sheets' pivoting, formulas, and charts to track rewards for the sales representatives and their performance within two different sales approaches. I also wrote extensive documentation to help us stay on the right track.

With Zapier, I automated generating leads and notifications for assignees in Slack after updates to statuses. I had two mentors and meetings once a week with each.

I worked with Plume on an enterprise app called Plume Workpass. I was part of an Android team of 10 and more than 100 people working on this app.

This was my first project with a clean architecture and a Kotlin multiplatform. I contributed to almost every part of the app—from the data layer through the domain and presentation to the UI. One very useful concept I learned was the mappers between each layer in the clean architecture.

I was in charge of bug fixing and implementing new features.
It was a one-month engagement, but in that time, I fixed all the bugs that came my way and helped finish one beta feature.

Jumprope was acquired by Linkedin in 2021.

This app is a personalized weight-loss program and I worked as a lead Android engineer in a team of five for two months.

The biggest challenge was to make changes in a legacy code and an architecture that didn't follow MVP principles as intended.

I worked on this mother-targeted app that ranked number one for downloads in its country. I co-developed the Android version from scratch and was mainly in charge of the UI. Delivering the required customization made this a fun project.

Technologies: Android, Analytics

TAKH Tutor AR is an AR/VR app that educates patients about their healthcare products.

I was the lead Android engineer using Minds and Assembly in a five-person team. I also worked closely with an in-house iOS developer and a 3D designer to match the experience. Another Android developer and I were in charge of finishing the Android app within tight deadlines.

Project Highlights:
• Developed my first commercial app with Kotlin and ARCore library.
• Built custom controllers that utilize only a drag gesture to successfully interact with an object in 3D space.
• Animated multiple VR/AR objects that moved with a click. I increased my knowledge of the technology tremendously throughout the project to make this possible.

Developed alongside two senior Android engineers. I was in charge of bug-fixing and implementing new features.

Although I was hired for short-term help, I learned a lot about Android Jetpack, Dagger 2, and Coroutines.

I worked as the sole senior Android engineer building an MVP of the app from scratch to publish, and I was in charge of publishing updates. This was one of two enterprise apps I developed for FocustApps.

Technologies: Android, Google Maps, REST, Git, HockeyApp, libGDX (3D), Firebase, Google Cloud Messaging

I was the sole senior Android engineer building the MVP of this app from scratch and publishing it along with updates. This was one of the two enterprise apps I developed for FocustApps.

Technologies: Android, Google Maps, REST, Git, HockeyApp, libGDX (3D), Firebase, Google Cloud Messaging

This was a fintech company with aspirations to become a private hedge fund.
I managed a team of four highly driven people, including one trader, one sales representative, one quant algorithm engineer, and an engineer in charge of automatizing processes.
• We developed an EA (expert advisor) with a hedging algorithm in MQL4. 90% of direction guesses are successfully closed in profit.
• I was in charge of organizing meetings, standups, work sessions, PR reviews, occasional EA feature development, accounting, and much more.
• Kanban organized in Trello with daily scrum standups.
• This was a side project for all of us.
• The biggest challenge was to get everyone on the same page and charge for the same goals.

A scientific research app for a skin disease called HVS.
I made the app from scratch with a Clean version of MVVM (Model View ViewModel) architecture.
Although I did regularly publish the app to Beta testers via Firebase Releases, I didn't stay on board to publish it live

Idyllic was in a pre-investment stage, and they needed a well-documented code review. In one week, I wrote more than 20 pages in a Google Doc file with a heavy emphasis on security. In addition to the in-depth security review, I also gave code improvement suggestions, composed bug reports, and showed design improvement according to Android design guidelines.

I delivered a speech titled "From Android Beginner to a 5-star Freelancer." This was my first professional talk, and I enjoyed speaking and sharing my knowledge about freelance work. After the speech, I obtained one business deal and a few developers approached me for a job, which was great.

The link attached is an article written about the talk (in Croatian).

I co-founded the TaxiCentral startup. Our goal was to make a super easy-to-use app for people who want to order a taxi in Zagreb. Basically, it was like Uber for taxi companies.

I was responsible for the entire development, rollout, and everything in between—working on the architecture, documentation, partial design, testing, publishing, and promotion. This was my first published application.

Technologies: Android

I developed the Android part while my college peers implemented the web crawling for this project. We won first place and received other perks like free office space for a year. The link attached is our pitch for the project (in Croatian).

BookBottles helps nightclubs easily manage reservations, table inventory, guest lists, client profiles, and transactions. I implemented the communication between the client and our developer on this project.

I built an Android app from scratch with a Parse-based back end for a pub-crawling brand for this project. I also set up everything so the founders could easily add events to the Parse back end.

Technologies: Android, Parse

The client's goal was to publish an Android pub-crawling app to the Google Play Store. They chose me to develop it after I reviewed the two previous developers' code.

I implemented the full development of the Android and Parse back end, completing the weekly tasks I had brainstormed with the client. I also migrated the app from Eclipse to Android Studio and the back end from DreamFactory to Parse.

Technologies: Android, DreamFactory, Parse, Facebook integration

The client's goal was to complete a partially (70%) completed app. They had previously employed four freelance developers who each, in turn, did some work before moving on. The code was in terrible condition and the client had a very tight schedule.

I worked on the UI changes, database, and REST API without improving the code because of the tight schedule and limited budget. The client delivered a fully developed app on time.

Technologies: Android, SQLite

I was in charge of building a POC (proof of concept) app in Flutter. This was my first professional project in Flutter, and I was amazed at how fast you can develop features and easily connect with the back end. Unfortunately, before I could finish the app, the budget for the project ran out.

Occasionally working on this app helps keep my priorities straight.
I'm learning Flutter and Firestore with it. A simple app that can have multiple projects and tasks inside each. You see only the highest priority tasks from each project on the home screen.