Bartosz is available for hire
Hire BartoszBartosz Kraszewski
Verified Expert in Engineering
Software Developer
Location
Bialystok, Poland
Toptal Member Since
August 20, 2019
Bartosz is a software engineer specializing in mobile application development. He focuses on code quality and adherence to standards and has several years of experience working in fast-paced, product-oriented environments, including Silicon Valley startups. Bartosz is also a co-founder of Mobile Bialystock: a local group for mobile technology enthusiasts.
Portfolio
Publicis Sapient
Flutter, Dart, Leadership, Mobile UI, APIs, Mobile Apps, Mobile App Development
Dropsource (via Toptal)
Dart, Firebase, Flutter, Mobile UX, Mobile Apps, Mobile App Development
Remojo (via Toptal)
Model View ViewModel (MVVM), Kotlin, Android, Mobile Apps...
Experience
Availability
Part-time
Preferred Environment
GitKraken, Sublime Text, Android Studio, MacOS
The most amazing...
...thing that I've built was an Android app that recognizes a user's meal from a photo and automatically calculates the calories and other nutrition details.
Work Experience
Lead Flutter Developer
2021 - 2022
Publicis Sapient
- Developed a new digital banking app from zero to the production release.
- Led the team responsible for user registration and customer onboarding.
- Implemented a custom framework to manage the registration process based on configuration files.
Technologies: Flutter, Dart, Leadership, Mobile UI, APIs, Mobile Apps, Mobile App Development
Flutter Expert
2020 - 2022
Dropsource (via Toptal)
- Implemented a high-quality, cross-platform application in Flutter.
- Designed and implemented a data model stored in Firebase.
- Used an innovative tool in Flutter development: a library called Monarch.
Technologies: Dart, Firebase, Flutter, Mobile UX, Mobile Apps, Mobile App Development
Senior Android Developer
2019 - 2021
Remojo (via Toptal)
- Designed, developed, and published a porn blocking app.
- Provided training and helped after the project was in the maintenance stage.
- Launched the app from the idea through the PoC to the production app.
- Implemented AI-based service, detecting pornography on the user screen.
- Designed and implemented both client and cloud-side subscription payment systems integrated with Google Play APIs.
Technologies: Model View ViewModel (MVVM), Kotlin, Android, Mobile Apps, Mobile App Development
Android Tech Lead
2016 - 2021
SoftwareHut
- Worked as an Android team leader in a distributed remote team—developing complex fitness/personal health applications with multiple versions. Responsible for planning, developing, refactoring, and also mentoring team members.
- Added new features to a complex codebase, including Kotlin support, introducing the multi-module architecture, delivering the MVP, and later implementing an MVVM approach and data binding.
- Optimized a customer app that reduced startup time and retrieved tons of lost animation frames. Profiled and analyzed the app's network performance with the AT&T Video Optimizer.
- Refactored user-profile-related classes to use repository pattern—introducing a local cache and lazy sync mechanism using WorkManager.
- Designed the initial Android app boilerplate used for new projects, implementing the necessary configuration dependency injection, and ensuring it has common utilities and is unit test friendly. The project was open-sourced as a starter app.
- Worked as a tech lead of the Android department, responsible for recruitment, helping the sales team, and estimating and analyzing projects.
- Led a Flutter project for a Polish betting company; also designed and developed Android and iOS applications handling account verification, betting, and payments.
Technologies: Java, Kotlin, Android, Flutter, Mobile Apps, Mobile App Development
Senior Android Developer
2015 - 2016
Mewe.com
- Implemented an emoji system before the EmojiCompact library was made public.
- Refactored a photo-stream module by introducing a new architecture and interfaces to reduce dependencies and simplify the codebase.
- Implemented the UI and backing logic for private and public groups.
- Optimized, implemented the new architecture, and reskinned all authorization and onboarding screens.
- Developed an internal framework for annotation-based widget coloring that was more maintainable than Android styles and could be updated in runtime.
Technologies: Java, Android, Mobile Apps, Mobile App Development
Co-founder | Lead Developer
2013 - 2016
Chemik.io
- Designed a multi-platform, complex data model of chemical compounds (SQLite).
- Created a native Android and iOS app (Java, Objective-C).
- Developed several types of utility software to facilitate database management (Java FX and Node.js).
- Created a marketing-and-user-acquisition strategy.
- Built mini-games and connected them to Google Play Games Services.
Technologies: Objective-C, JavaFX, Android, SQL, JavaScript, Kotlin, Java, Mobile Apps, Mobile App Development, Mobile App Design
Software Engineer | Team Leader
2013 - 2015
OwnedOutcomes
- Worked on multiple prototypes in a fast-changing, customer-oriented environment, specifically the US healthcare startup market.
- Developed a kiosk app for tablets (native Android); built a secure platform for performing patient screening and integrated the connectivity and security systems.
- Contributed to the build of Tangram Clock (mostly the UI): a native Android app for cognitive impairment screening.
- Built an internal framework for publishing patients' wellness screenings, written in GWT and Spring.
- Designed and worked as a part of a team on a web app for annual wellness visits (both the patient and doctor sides).
Technologies: PostgreSQL, MongoDB, Angular, JavaScript, Android, Spring, Java
Database Developer
2012 - 2013
Tower Group
- Created automated ETL jobs that filled out data warehouse with insurance claim information.
- Built an automated-reporting service to compare financial data before and after data migrations.
Technologies: Microsoft SQL Server, SQL
Junior Java Developer
2011 - 2012
GRC Solutions
- Designed and implemented a workflow management engine and was responsible for creating custom document acceptance flows.
- Implemented multiple features in GRC's workflow software which automated the document workflow system.
- Integrated a type of role-analysis software with SAP which red current user roles from the system and exported it to an internal database.
Technologies: Spring, Microsoft SQL Server, CSS, XHTML, Java
Experience
[NDA] Exercise Database
I developed an offline-first exercise database for Android. It allows a user to use ready-to-use workouts (exercises, video workouts) and also create their own.
[NDA] Nutrition Manager
I built an Android app that makes daily nutrition tracking easy. It has a built-in meal database and the ability to generate meal plans and track calories and nutrition details.
[NDA] Fitness Tracker
I developed a complex app allowing the user to track daily activity data including the number of steps, your nutrition, commute time, exercises, heart rate, and quality of sleep.
Chemik Android App
I developed a native Android app for learning chemistry. A user can use the periodic table like a keyboard to check information about elements and compounds. It also has built-in mini-games to learn the periodic table and calculators to solve chemistry tasks.
Mewe Android App
https://play.google.com/store/apps/details?id=com.mewe&hl=enI built an Android application for a privacy-first social network.
Tangram Safe
I built a secure kiosk app that acts as a launch pad for multiple screening applications to be used in hospitals.
Skills
Languages
Dart, Java, Kotlin, SQL, Objective-C, XHTML, CSS, JavaScript
Frameworks
Android SDK, Flutter, JUnit, Spring, Angular, Dagger 2
Libraries/APIs
Android API, RxJava 2, Node.js
Paradigms
Mobile Development, Agile, Model View ViewModel (MVVM), Functional Programming, Mobile App Design
Platforms
Mobile, Android, iOS, Firebase, MacOS, JavaFX
Other
Senior Android, Mobile Apps, Mobile App Development, Mobile Architecture, APIs, Architecture, GitKraken, Software Engineering, Computer Science, Artificial Intelligence (AI), OOP Designs, Leadership, Mobile UI, Mobile UX
Tools
Android Studio
Storage
SQLite, MongoDB, PostgreSQL, Microsoft SQL Server
Industry Expertise
Project Management
Education
2012 - 2014
Master's Degree in Computer Science
Bialystok Technical University - Białystok, Poland
2008 - 2012
Bachelor of Engineering Degree in Computer Science
Bialystok Technical University - Białystok, Poland
Certifications
JANUARY 2017 - PRESENT
Divide and Conquer, Sorting and Searching, and Randomized Algorithms
Stanford University via Coursera
JANUARY 2017 - JANUARY 2020
Associate Android Developer
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