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Patryk Matuszewski, Software Developer in Wrocław, Poland
Patryk Matuszewski

Software Developer in Wrocław, Poland

Member since December 18, 2013
Patryk is a software engineer who loves creating new things. He develops efficient solutions to meet client requirements. He enjoys helping clients come up with clear visions of their needs. He loves to make the whole development process clear and efficient, implementing the best available options for a specific problem—he has experience using approaches like continuous delivery, Scrum, TDD, ATTD, BDD, and extreme programming.
Patryk is now available for hire


  • Toptal Client
    Ethereum, Quorum, Java, Spring Boot, Spring Cloud, Web3j, MongoDB, Kafka
  • Coinbooth
    Bitcoin, Blockchain, Bcoin, Node.js
  • Synkt Games
    Ethereum, Solidity, Truffle, Zeppelin, Remix


  • Java, 8 years
  • JavaScript, 6 years
  • Android SDK, 6 years
  • Spring MVC, 6 years
  • Test-driven Development (TDD), 3 years
  • AngularJS, 2 years
  • Ethereum, 1 year
  • Solidity, 1 year
Wrocław, Poland



Preferred Environment

IntelliJ, Android Studio, MacOS

The most amazing...

...project I've worked on is the back-end of the biggest worldwide VOD-delivery company.


  • Lead Developer

    2018 - PRESENT
    Toptal Client
    • Gathered and analyzed requirements with the client.
    • Helped organize the project timeline by introducing Agile methods.
    • Worked closely with the front-end team to help integrate with the back end.
    • Planned and implemented the sync layer between the back-end application and Ethereum private network which helped query data from the blockchain using simple MongoDB queries.
    • Planned and implemented the back-end service, which was the gateway between the Ethereum network and the application—used an event-driven approach, with Spring Cloud and Kafka solutions.
    Technologies: Ethereum, Quorum, Java, Spring Boot, Spring Cloud, Web3j, MongoDB, Kafka
  • Senior Blockchain Engineer

    2018 - 2018
    • Created an integration layer in Node.js with BitcoinCash network.
    • Analyzed and gathered requirements with the client for a payphone-like application.
    • Created the design and the architecture of the application and implemented them in the working prototype.
    • Designed the REST API, which could have been used by different types of clients.
    • Analyzed and made plans about the future development of the application.
    Technologies: Bitcoin, Blockchain, Bcoin, Node.js
  • Senior Blockchain Engineer

    2018 - 2018
    Synkt Games
    • Worked closely with the client on the white paper, and proposed improvements to the economic model.
    • Implemented Crowdsale contract for ICOs.
    • Implemented ERC20 and utility smart contracts.
    • Created the full test suite for the codebase (Truffle).
    • Deployed and tested smart contracts in the private blockchain.
    Technologies: Ethereum, Solidity, Truffle, Zeppelin, Remix
  • Software Engineer

    2017 - 2018
    • Created a flexible solution to generate questionnaires from data taken from external sources.
    • Implemented an audio/video framework for further integration with the company's AI system.
    • Worked closely with team members to gather business requirements and transform them into application features.
    • Researched Google Fit abilities which could be used to improve application usability.
    • Worked on the application's architecture and provided detailed feedback.
    Technologies: Java 8, Android, RxJava, Google Fit
  • Technical Project Lead

    2017 - 2018
    • Initialized and analyzed the business elements of a real-time web-based game project for the education sector.
    • Created and realized the plan of development using an iterative approach and tight communication with the client.
    • Analyzed and eliminated all risks and proposed the scope which gave the best outcome for the client.
    • Used highly efficient approaches (Akka, Microservices, Cassandra) to meet real-time requirements and supported multiple teams playing at the same time.
    • Proposed and implemented event sourcing architecture for the system, which generated new tools and brought about high fault tolerance and improved performance.
    Technologies: Java, Spring, Akka, Microservices, Cassandra, RabbitMQ, MySQL, WebSockets
  • Back-end Lead Developer

    2015 - 2018
    Toptal Client
    • Prepared and implemented scalable architecture from scratch.
    • Implemented an efficient Scrum planning process in the project.
    • Worked as Scrum master and tried to help the rest of the team understand Scrum processes.
    • Created the continuous deployment environment by implementing full automatic regression testing suites.
    • Helped to analyze and understand all business concerns and how they impact the final product.
    Technologies: Java, Java EE, Google App Engine, AWS, JBehave, Jenkins, Docker
  • Lead Software Developer

    2017 - 2017
    • Elicited client requirements, prepared the project plan, and helped analyze all business requirements/rules.
    • Created the UI/UX of the application based on existing iOS design, considering Material Design guidelines.
    • Implemented an effective drawing screen solution which is easy to use for kids.
    • Created a sufficient automatic testing solution, which used remote real devices to provide the best testing results for application use cases.
    • Published the application in the Play Store with two versions and minimum defect level, supporting the greatest possible number of devices and quickly resolving any existing issues.
    Technologies: Android, RxJava, Dagger, Material Design, Espresso
  • Software Engineer

    2016 - 2017
    5AM Solutions
    • Helped to set up BDD strategy for an extensive testing environment.
    • Worked on microservices to create clear and consistent endpoint contracts.
    • Helped implement a data service to handle a massive amount of ingoing data using cloud solutions.
    • Used Spring templates and Feign to create communication channels between different microservices.
    • Worked on a Spring Cloud configuration to achieve the best fault tolerance and availability level under conditions specific to the domain model.
    Technologies: Java, Spring MVC, Spring Boot, Spring Cloud, Kafka, AngularJS, Docker, Cloud Solutions
  • Android Developer

    2015 - 2016
    • Improved application quality by finding and resolving most critical issues.
    • Introduced Scrum processes.
    • Helped to understand how the software development process should look and started implementing a solution tailored for this specific startup project.
    • Collaborated with back-end developers to find the best options to achieve best performance from mobile and server perspectives.
    • Helped to find a business model and how to grab customers.
    Technologies: Android, Robolectric, Android Annotations, Dagger
  • Back-end Lead Developer

    2015 - 2016
    • Prepared and implemented scalable architecture from scratch.
    • Implemented an efficient Scrum planning process in the project.
    • Helped to find and analyze all business concerns.
    • Worked with mobile developers to achieve the best performance from the server side.
    • Used TDD and created a base for BDD to have a fully-integrated deployment environment.
    Technologies: Java, JEE, Google App Engine, AWS, NoSQL
  • Software Engineer

    2014 - 2015
    Airline Company [NDA]
    • Created a robust architecture for a ticket management application for the company's customers.
    • Helped improve the Scrum process.
    • Helped with business analysis.
    • Worked and communicated in an international team in the client's workplace (abroad).
    • Implemented and released the app, used by more than 100k people around the world.
    Technologies: Android 4, Java, JUnit, Calabash
  • Software Engineer

    2011 - 2015
    VOD-content Delivery Company
    • Integrated third-party platforms with the system by VXSLs.
    • Wrote unit/integration tests.
    • Maintained the existing codebase.
    • Discussed and proposed new solutions.
    • Fixed critical bugs.
    Technologies: Java, Java SE, Spring, Java EE, XSLT, JMS, JPA
  • Software Engineer

    2011 - 2011
    • Created an integral SEO system to support existing customers.
    • Maintained existing solutions.
    • Helped to create a clear vision what should be done in the future.
    • Learned and worked in unknown previously technologies to created better solutions (no silver bullets).
    • Worked with other people in the team to achieve common goals.
    Technologies: PHP 5, Zend Framework 1, PHPUnit, Doctrine 1, C#


  • Blockchain IoT (Development)

    An open source solution to integrate IoT into Ethereum. I am working on the contracts' implementation as well as the general idea.

  • Atomize Software Spin Framework (Development)

    I was working on the ORM-like solution to provide functionality handling advanced filtering or searching rules for the data synchronized with the back-end. The solution had to be effective because the app processes the massive amount of the data on the client side. Also, I helped the client to decide what solution will be the best in this particular context.

  • | Startup (Development)

    We (four members in a team) tried creating software to support management of LED ad banners on the streets. We wanted to connect banner owners with advertisers and create a new way to increase profits. The project won a B2B award on Startup Weekend Poznan (2011) but was cancelled due to lack of funding after a year.

    - Led a four member team.
    - Handled business analysis for the project.
    - Made pitches for investors.
    - Implemented the back-end using cutting-edge technologies (Symfony 2, PHP 5.3, MongoDB).
    - Created a suite of full automatic acceptance/unit tests (Behat, PHPUnit).
    - Implemented a mobile client (Android SDK 2.3).

  • Newspaper Mobile App in Android (Development)

    I worked on the Android mobile app for one of the most recognized newspapers in the world. My major goal was to reduce a number of bugs (the first version of the app had a couple of thousands crash reports on Crashlytics).

    To achieve that, we improved the automation testing process (added more unit tests, fixed existing one), fixed all memory management issues (like invalid bitmap processing, lack resources cleaning) and identified all use cases which can cause problems. At the end of the project, the number of crashes were reduced about 70-80% and the app started getting more positive reviews in Google Play Store.

  • Internal Software for an Audit Company (Android 3.0) (Development)

    I created an Android 3.0 application on tablets to support audit stores for a global performance improvement company.

    - The application contains questionnaires that are created dynamically by a server-side application and are needed to implement an optimal solution to exchange data between a server and web application.
    - I needed to create a robust software architecture to support multiple pages and dynamic views with extensive user input support (open, close, multiple-choice question, and camera support) and multimedia support (video player, etc.)
    - I implemented support for many types of tablets (Samsung, Sony, Asus).

  • VOD Software (Development)

    Worked for the largest VOD-content delivery company in the world to improve the existing system and implement new functionality.

    Technologies: Java SE, JEE, Spring, XML, XSLT

  • (Development)

    Created an Android application for a Polish startup allowing users to find a nearby medical specialist.

    - Led a three person team.
    - Conducted business analyses with the customer (created a list of features, wireframes, and a domain model).
    - Prepared a specification of a back-end API that was needed to communicate between an Android app and a back-end server (used RESTful best practices).
    - Handled project management using Agile methodology and TDD.
    - Implemented the application using cutting-edge Android technologies (API 4.1, AndroidAnnotations, RoboGuice, Robolectric).

  • Software for Analyzing Mobile Application Stats | PHP 5 (Development)

    I created a web platform for analyzing mobile application stats. We needed to create a complex solution to gather statistical information from many kinds of mobile applications (e.g., how much time users spend on each page or how many times users click on a banner).
    - I implemented a library to communicate with a back-end API for J2ME. It featured optimized operations for low-memory devices and support for a wide range of mobile phones.
    - I created a MySQL sharding module for a back-end system (PHP 5.3, MySQL). It required a scaling feature for a growing numbers of users and applications.
    - I implemented a dynamic web interface on the user side (stats are updated in almost real-time).

  • Leagues Management Application [PHP] (Development)

    Created a PHP application for a small sports company to support management football (soccer) leagues.

    - Architected the app
    - Deployed a small iterative process to control requirements changes
    - Implemented the app based on the project and client requirements
    - Set up a production environment (Apache 2, PHP FPM, ACL, MySQL)

    Technologies: PHP 5.3 + Doctrine + Zend Framework 1 + Facebook API, jQuery, PHPUnit

  • Tax Refund Management Application (Development)

    Created an application to support and manage tax refunds in the UK

    - Worked directly with the client to settle all requirements
    - Implemented a small iterative development process to handle changes
    - Architected the app
    - Implemented the app based on existing law regulations
    - Set up a production environment (Apache 2, Nginx, PHP FPM, MySQL)

    Technologies: PHP 5.3 + Doctrine 2 + Zend Framework 1 +
    Doctrine 2 + Zend Framework 1 + jQuery + PHPUnit

  • BlackBerry 6 Project (Development)

    I created a quiz application for an airline related company (Tech: Java 1.4, BlackberrySDK 6, Facebook API, JS, HTML). During the project, I needed to learn a completely new SDK and use this knowledge in a business environment.

    - The UI implementation (JavaScript, HTML) is based on existing wireframes and included support for many types of devices.
    - I created a library to communicate with Facebook API in Java 1.4. I needed to use a limited edition of Java specifications to create a robust solution to support many user behaviors, such as image uploading, adding texts to the Wall, inviting friends, and sending messages to friends. The application worked on 3G.

  • Android 2.2 Project (Development)

    An Android 2.2 news feeder for one of the biggest broadcasting companies in the world. I needed to include support for an Arabic language-based device and fixed bugs in the existing legacy code.


  • Languages

    JavaScript, Solidity, Java, Kotlin, Scala, Python, PHP, SQL, Clojure
  • Frameworks

    Spring Security, Truffle, Android SDK, Spring Boot, Spring MVC, Spring Android, AngularJS, JPA, JavaServer Faces, Hibernate
  • Libraries/APIs

    Java Collections, Android API, Node.js, Java Servlets, Hystrix, React, Backbone.js, Facebook API, jQuery, Twitter API, React Redux
  • Tools

    PhpStorm, IntelliJ, Eureka, Apache ZooKeeper, Eclipse IDE, JHipster, Android Studio, WebStorm
  • Paradigms

    Continuous Integration (CI), Behavior-driven Development (BDD), Iterative Programming, Agile Software Development, Object-oriented Programming (OOP), Unit Testing, Design Patterns, Test-driven Development (TDD), Functional Programming, Microservices, Concurrent Programming, Distributed Programming, Pair Programming, Domain-driven Development
  • Platforms

    Blockchain Platforms, Blockchain, Ethereum, Google App Engine, Android, Linux, Kubernetes, Docker, Netflix, Amazon Web Services (AWS), Windows
  • Other

    Ethereum Smart Contracts, Spring Cloud, Software Architecture, Netflix OSS, Apache Commons
  • Storage

    Redis, MySQL, MongoDB, Google Cloud, AWS S3, Elasticsearch, Memcached


  • Bachelor's degree in Computer Science
    2017 - 2021
    Polish-Japanese Academy Of Information Technology - Warsaw
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