Aleksandar Tomislav Markovic, Developer in Belgrade, Serbia
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Aleksandar Tomislav Markovic

Verified Expert  in Engineering

Software Developer

Belgrade, Serbia
Toptal Member Since
January 26, 2016

Aleksandar has been a software developer for about ten years, doing everything from Assembler programming to web development and, more recently, ReactNative and React development. He has done work for companies like Sony Mobile, Goldman Sachs, Bosch, Plantronics, and Bottle Rocket Studios. His communication skills and solid development work make him avaluablel asset to any project.


Goldman Sachs - Main
Android, RxJava 2, Model View Intent (MVI)
Kotlin, Android, Bluetooth, PostgreSQL
Android, React Native, React




Preferred Environment

Android, React Native, React, JavaScript

The most amazing...

...thing I've done is use Bluetooth Low Energy devices for indoor navigation. I worked on the YouVerison Bible Android app with 100+ million downloads.

Work Experience

Android Developer

2021 - 2023
Goldman Sachs - Main
  • Became a part of different teams that were maintaining the Marcus Android app. Integrated the app with Plaid services.
  • Performed a complete rebrand of the app, changing the colors and fonts and paying special care to accessibility issues.
  • Rewrote the app in the new architecture, switching from Conductor and Epoxy to Jetpack Compose.
Technologies: Android, RxJava 2, Model View Intent (MVI)

Senior Android Developer

2019 - 2020
  • Worked on integrating Bluetooth iHealth devices for measuring blood pressure and glucose in the blood.
  • Implemented graphs for displaying blood pressure and glucose results to patients. Users can filter results by day, week, month, or year.
  • Worked closely with the designers to make the app intuitive and easy to use, so that users can easily check their next trial visit and their available payments.
  • Integrated an AWS Cognito service for user authentication. Integrated continuous integration using CircleCI and Fastlane for easy distribution of test and production releases, and also integrated Sentry service for error tracking.
  • Maintained and published the app on Google Play Store.
Technologies: Kotlin, Android, Bluetooth, PostgreSQL

Senior React Native Developer

2018 - 2020
  • Maintained and implemented new functionalities into the existing CafeWell app.
  • Converted the app's code completely to support the newest AndroidX libraries and also converted the remaining parts of code written in Java to Kotlin.
  • Helped the team improve and stabilize back-end services written in Java, Ruby, and Node.js.
  • Rewrote the old Android and IOS app in React Native.
Technologies: Android, React Native, React

Senior Android Developer

2017 - 2019
  • Built Temptime's Android app using the new Camera 2 APIs to detect the changes in the color of a temperature sensor that is injected on a QR barcode.
  • Took part in a larger project to develop the first miniaturized technology to monitor temperature exposure of vials containing the oral polio vaccine, which satisfies the World Health Organization’s (WHO) PQS VVM performance specification.
  • Used the latest technology stack when it comes to the app's deployment.
Technologies: Java, Android, PostgreSQL

Senior Android Developer

2017 - 2018
  • Rewrote the app using MVVM and Android architecture components.
  • Integrated QR barcode detection and an intercom.
Technologies: Java, Android

Android Developer

2017 - 2017
YouVersion (via Toptal)
  • Wrote tests and made sure that the app's main functions were properly implemented.
Technologies: MVVP, Room, Dagger 2, OkHttp, Gradle, GitLab, Espresso, Android, Kotlin

Android Developer

2017 - 2017
Pangea (via Toptal)
  • Created an Android app to communicate with a Bluetooth-connected watch that can measure heart rate and level of oxygen inside a patient's blood.
  • Processed byte data received from the device and transformed the data into usable Java classes.
  • Made login/register flow, syncing data with the server.
  • Enabled the back-end to control the device thorough the Android app.
Technologies: Espresso, Retrofit 2, Gradle, RxJava 2, REST, Android, Bluetooth

Senior Android Developer

2016 - 2017
FuboTV (via Toptal)
  • Created a streaming app that can play sports channels on the mobile device, save them for later watching, and list all the sports events two weeks in advance.
  • Built the app from the ground up, proposing tools, libraries, and overall solutions to make the app and code base in a clean and testable way.
Technologies: Model View Presenter (MVP), Glide, Retrofit, Dagger 2, Gradle, Java, Android

Senior Android Developer

2016 - 2016
Pulsr (via Toptal)
  • Created a reusable, cross-platform social network app that can propose events to go to or guide you to the important places inside the selected city.
  • Worked with an existing codebase, refactoring the app to be as testable as possible.
  • Introduced the Google Maps API.
Technologies: Clean Architecture, Glide, Realm, Retrofit, Java, Android

Senior Android Developer

2016 - 2016
  • Worked on a device that connects to the car's onboard computer over Bluetooth using an ODB interface and then extracts, process, and displays all the relevant data like errors on the car, trip logs, last parked position, etc., on the Android device.
Technologies: Bluetooth, Java, Android

Senior Android Developer

2015 - 2016
MERA Software Services
  • Worked on an app that streams various TV content to mobile devices using HLS and Media Player frameworks.
  • Integrated different type of analytics (Nielsen, Omniture and Comscore) to the existing video player.
Technologies: ExoPlayer, Glide, Dagger, GSON, Retrofit, Android SDK, Java

Android Developer

2014 - 2015
  • Worked for Sony and contributed to projects for Plantronics.
  • Developed features for a smart Bluetooth fitness watch, using Bluetooth Low Energy (BLE) for communication between device and phone.
  • Implemented features and maintained the calendar and alarm applications for Sony Mobile.
  • Developed a small Android app for indoor navigation using Bluetooth Low Energy (BLE) beacons.
Technologies: Android SDK, Java

Android Developer

2012 - 2014
Mitec, d.o.o
  • Developed a chat application with integrated data encryption.
  • Developed a SQLite database and complete UI of the application.
Technologies: Android SDK, Java

Web Developer

2009 - 2009
Univerzijada 2009
  • Built a dynamic picture gallery and a scoreboard with live results.
  • Maintained the Univerzijada website.
Technologies: MySQL, PHP

Awe Everywhere

AWE is the powerful app platform for branded video delivery and engagement across all major platforms.

Sony Mobile Calendar and Alarm

Custom Sony Mobile Calendar and Alarm app.
2002 - 2013

Bachelor's (Hons) Degree in Electrical Engineering and Computing (Computer Science and Informatics)

Faculty of Mathematics - Belgrade, Serbia


Retrofit, Retrofit 2, REST APIs, RxJava 2, SQLBrite, RxJava, React, GSON


GitLab, GitHub, AutoValue, Eclipse IDE, Android Studio, Gradle, ExoPlayer


Dagger 2, Android SDK, React Native, Dagger, Glide, Espresso


Kotlin, JavaScript 6, Java, PHP, SQL, Python, C, JavaScript, TypeScript, C++


Agile Software Development, Model View Presenter (MVP), Model View ViewModel (MVVM), Clean Architecture, Android Material Design, REST, MVVP, Model View Intent (MVI)




MySQL, PostgreSQL, Realm


GitFlow, OkHttp, Video Streaming, Bluetooth, Room, WebSockets

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