Nikita Kraev, Mobile Developer in London, United Kingdom
Nikita Kraev

Mobile Developer in London, United Kingdom

Member since August 25, 2020
Nikita is a highly skilled mobile developer who can drive a part-time or hourly project of any complexity from estimations to completion. Nikita is ready to join Android, Flutter or React Native projects or teams to deliver exceptional quality in short periods of time. Where Nikitia excels is in working closely with clients while explaining all his steps, decisions, and trade-offs in an understandable way.
Nikita is now available for hire


  • Voi Technology AB
    CircleCI, Mapbox, Dependency Injection, Coroutines, Kotlin, Android
  • Rebtel Networks AB
    Material Design, Firebase, Reactive Streams, Dagger 2, RoomDB...
  • Urbest
    ClojureScript, Clojure, React Native, RxJava 2, GraphQL, Kotlin, Android



London, United Kingdom



Preferred Environment

MacOS, Linux, IntelliJ IDEA, Android Studio, Visual Studio Code

The most amazing...

...project was the one where I narrowed the choices from three mobile app architectures into one which was explicitly built to solve customer problem.


  • Senior Android Developer

    2019 - 2020
    Voi Technology AB
    • Migrated the legacy codebase into modern and coroutine-based reactive Kotlin code. The project took three months to develop but in the end it allowed us to iterate 2.4x times faster than before (about 3.1W vs 7.66W before per feature).
    • Developed a new Mapbox-based map layer which rendered independently from server responses and improved our TTI (time to interact) by more than 350 milliseconds.
    • Researched instruments and options and picked Flutter when creating a new employee application. That allowed me to iterate faster while being alone, comparing to two other developers who worked together on the same project.
    • Improved Agile processes in the team, resulting in a reduction of unnecessary meetings, better product owner awareness on progress, and enabled new tools for project scope visibility.
    • Helped iOS engineers to set up continuous integration and continuous delivery using CircleCI.
    Technologies: CircleCI, Mapbox, Dependency Injection, Coroutines, Kotlin, Android
  • Android Developer

    2018 - 2019
    Rebtel Networks AB
    • Led a development team of three Android engineers when creating a brand-new fintech banking app from scratch in very strict deadlines.
    • Introduced Kotlin to the codebase by writing about 400 tests following the language's best practices and showcased them to the team.
    • Created a feature toggle mechanism from scratch, bundling it into a legacy app that allowed us to remove dead code and canceled experiments 7x faster! (3D vs 3W before).
    • Led Material Design discussions with the lead designer which helped us to build a visually stunning custom application while keeping the native Android UX.
    Technologies: Material Design, Firebase, Reactive Streams, Dagger 2, RoomDB, Code Architecture, Kotlin, RxJava 2, Android
  • Lead Android Developer

    2017 - 2019
    • Migrated an old and slow legacy Java app into Kotlin, reducing the lines of code (LOC) from 58,000 to just 19,000.
    • Introduced dynamic module loading into native Android by splitting DEX files and ordering them by the module requirements. That improved our TTI (time to interact) by more than 1,300 milliseconds.
    • Initiated the research and A/B testing on a small number of users to drive UX and UI discussions by metrics without being subjective.
    • Participated in the launch of a React Native app rewrite (ClojureScript and React Native) while maintaining, extending, and bug-fixing a Kotlin version in parallel.
    Technologies: ClojureScript, Clojure, React Native, RxJava 2, GraphQL, Kotlin, Android


  • Voi Scooters App

    A Kotlin and coroutines-based application for the Stockholm startup, Voi. I was one of the lead Android developers and participated in the app re-architecture and unidirectional data flow. That allowed us to create new features much faster which is essential for a startup.

  • Majority

    A Kotlin-based app for the Swedish company, Rebtel. This is a digital banking application specifically targeted for immigrants. Everything was created in a very tight deadline. But we did impossible and with only three Android developers, we launched this fresh looking and feature-rich application in just six months!


  • Languages

    Kotlin, GraphQL, JavaScript, TypeScript, Clojure
  • Frameworks

    React Native, Flutter, Dagger 2, ClojureScript
  • Libraries/APIs

    RxJava 2
  • Tools

    Flow, Android Studio, IntelliJ IDEA, CircleCI
  • Platforms

    Android, Firebase, Visual Studio Code, Linux, Mapbox, MacOS
  • Other

    Coroutines, Code Architecture, Reactive Streams, Material Design
  • Storage

  • Paradigms

    Dependency Injection


  • Bachelor's Degree in Computer Science
    2015 - 2017
    Innopolis University - Innopolis, Russia

To view more profiles

Join Toptal
Share it with others