Michal Mikolajczyk, Blockchain Developer in Warszawa, Poland
Michal Mikolajczyk

Blockchain Developer in Warszawa, Poland

Member since September 17, 2014
Michal is a senior software engineer and community leader for Toptal Warsaw. He communicates well and takes the initiative needed to help startups scale. Michal writes clean, functional code, automates infrastructure, and enjoys coordinating and scoping tasks. A former digital nomad, Michal speaks at conferences, and writes articles for the Toptal Blog. His professional interests include blockchains and artificial intelligence.
Michal is now available for hire




Warszawa, Poland



Preferred Environment

Google Cloud, Travis CI, GitHub, Kubernetes

The most amazing...

...app I've built was Nowness.com (via Airnauts), which was nominated for a Webby Award 2015, and won Pixel Award and Pixel Award People's Choice.


  • Lead Engineer

    2020 - PRESENT
    Slidegrin, LLC
    • Set up serverless JAM stack application architecture on AWS Amplify.
    • Connected user pools with AWS IAM roles to manage users with AWS Cognito, in a multi-tenancy environment, including role-based access control permissions.
    • Set up live synchronization between sessions using GraphQL subscriptions with AWS AppSync.
    • Built an image manipulation editor supporting HTML Canvas with SVG and allowing exporting to raster and vector formats including PDF.
    • Established CI/CD pipelines with Amazon Amplify, CodeBuild, and CodeDeploy.
    • Built the serverless front-end app using Next.js and React with TypeScript.
    • Established unit and integration testing strategies with Jest, Enzyme, and React Testing Library.
    Technologies: Amazon Web Services (AWS), SVG, Canvas, React, Serverless, AWS AppSync, AWS DynamoDB, Amazon Cognito, AWS Amplify, AWS
  • CIO

    2018 - 2020
    Multichain Ventures
    • Developed web apps using React, Node.js, and Vue.js.
    • Developed mobile apps using Expo and React Native.
    • Developed blockchain DApps using Waves, Ethereum, and Quorum blockchains.
    • Built a payment service provider API.
    • Managed a team of up to six engineers.
    • Created the information and technology strategies.
    • Introduced engineering standards, including Git flow, CI, unit testing, and containerization.
    • Introduced in-app user behavior monitoring based on funnels, user acquisition, retention, and monetization.
    • Developed integration mechanisms, relying on open-source technologies.
    • Implemented supply-chain visibility tools.
    Technologies: Blockchain, Kubernetes, JavaScript
  • Co-founder

    2018 - 2020
    • Managed hundreds of applications on AWS and Google Cloud Platform.
    • Administered Kubernetes clusters.
    • Built an eCommerce storefront with Vue Storefront with Progressive Web App PWA technology.
    • Set up Istio service mesh.
    • Automated processes, including monitoring and alerting.
    • Introduced site reliability engineering principles.
    • Adopted apps to cloud native computing.
    • Delivered a highly available platform as a service.
    Technologies: Site Reliability Engineering (SRE), Istio, Kubernetes
  • Lead Engineer

    2018 - 2018
    William Hill
    • Released a new product.
    • Led a team of developers.
    • Worked closely with QA and BA.
    • Developed performance benchmarks and improved on them.
    • Maintained, documented, and released three applications in a corporate environment.
    Technologies: Cloud Services, React, JavaScript
  • Founder & CEO

    2017 - 2018
    Viking Garage
    • Founded the startup, bootstrapping it for nine months and building a team of six people.
    • Released the product within the first three months.
    • Led development, with over 55,000 lines of open-source code.
    • Organized a conference that resulted in the formation of an open source blockchain IoT project.
    • Presented at three international conferences.
    • Expanded the reach of the project from Poland to Spain, Portugal, and Indonesia within eight months.
    Technologies: Blockchain
  • Senior Software Engineer

    2016 - 2017
    Maxwell Health
    • Worked consecutively on four teams, to date.
    • Coordinated work between different teams and team leaders.
    • Planned, scoped, and groomed tasks for teams and peers.
    • Developed front-end and back-end components.
    • Set up automated infrastructure (devops: Docker, Terraform).
    • Planned architecture.
    • Helped clarify peer communication.
    Technologies: Docker, PHP, DevOps, JavaScript
  • Software Engineer

    2012 - 2017
    • Architected and developed a new client-side web application for an existing, settled organization with hundreds of thousands of users interested in the fashion industry and indie art in Western (English) and Chinese territories (collaboration with UX designers and API engineers).
    • Architected and integrated six external databases into one system, a MongoDB/Elasticseach search engine for the Museum of Polish Jews.
    • Created an AngularJS client and a Node.js/SQL Server API for an event calendar app used internally by the Museum of Polish Jews.
    • Developed an AngularJS client for LimeSurvey, an open source survey CMS that exposed an RPC API for a national university (Warsaw School of Life Sciences).
    • Collaborated with UI/UX designers for the purpose of designing and subsequently developing responsive, holistic front ends for Krytyka Polityczna (a major alternative journal) and Bankwatch (an IFI focused, international NGO).
    • Created and led a developer team, introducing Agile, Scrum, Kanban, behavior-driven design, and test-driven development methodologies into the workspace.
    • Collaborated as a Drupal developer on two subsequent projects for West Pomeranian Voivodship and Unizeto Technologies, integrating Drupal and Apache Solr.
    • Delivered a high-availability Drupal app and server environment for the Educational Research Institute (Ministry of Education); the project is being designed to allow registration of all Polish schools and also to provide Microsoft Excel (VBA) tools to aid teachers.
    • Delivered two Drupal CMS-based projects for the Warsaw City Council and the Warsaw Zoological Garden: Wild Bird Refuge and CITES Convention sites and HD multimedia.
    • Designed and created Apache Solr search algorithms, used to drive the UX of a 2013 international MatEXPO, an international construction site machinery convention.
    • Architected and developed a RESTful API for an iPhone app, fully cloud-based (Heroku and S3) and running in a continuous integration environment using Codeship.
    • Architected, designed in collaboration with UI/UX artists, and developed a responsive AngularJS web app aimed at mobile devices for London beauty therapists.
    • Delivered dozens of small and mid-sized custom Drupal CMS commercial projects.
    Technologies: Drupal, MongoDB, AngularJS, Node.js, JavaScript
  • Senior React Developer

    2015 - 2016
    Praesens (via Airnauts)
    • Developed a React/Redux app from the ground up.
    • Introduced state-of-the-art technology and stable technology into a new project.
    • Architected the app structure, including the front-end codebase, front-end API proxy and server, deployment pipeline, and CI.
    • Translated and/or reused components from a prototype version, which was based on the Middleman JS framework.
    • Worked alongside the CTO, introducing best practices, robust solutions, to all aspects of the app, from UI/UX to API communication and authentication.
    Technologies: Babel, Webpack, JavaScript, Emacs, Redux, React
  • Lead UI Developer

    2015 - 2016
    • Entered an existing startup, introduced effective solutions, and then took the role of UI team lead.
    • Improved the end product, placing the UI team ahead of the curve.
    • Introduced a standard, predictable release schedule, based on a Git flow of develop, release, and production.
    • Built a highly effective team with specialized roles, allowing the members to gain complementary skills.
    • Introduced unit testing and E2E testing within a continuous integration environment.
    Technologies: Functional Programming, Scrum, Test-driven Development (TDD), GitFlow, AngularJS
  • Software Developer

    2014 - 2016
    Metavaluate (via Toptal)
    • Upgraded a legacy app in terms of structure, performance, design, user interface, and experience.
    • Used separate threads in the browser to achieve non-blocking, heavy filtering, and sorting of large data sets.
    • Added models and controllers on the API through Sails.js.
    • Added a caching layer through Redis.
    • Added support for unit and E2E tests and provided multiple tests to be included in a CI environment.
    • Continued support for the project as consultant.
    Technologies: Redis, MongoDB, Sails.js, AngularJS, JavaScript
  • Software Engineer

    2014 - 2016
    • Architected and built a large AngularJS app used by hundreds of thousands of users every month, in English and Chinese.
    • Added support for different video and audio content providers.
    • Created a robust SEO solution, using lightweight web services and built with Go.
    • Provided configuration modules to the CMS, which allowed for the preparation of content to show in the client app.
    • Supported all modern devices, with multiple responsive break points.
    • Added integration with multiple social networking services, including several from China.
    • Added support for a recommendation service, through a light web service built with Go.
    Technologies: Media, Go, Node.js, AngularJS, JavaScript
  • Software Engineer

    2015 - 2015
    Heffernans Insurance (via Toptal)
    • Architected a robust, reactive system.
    • Engineered a minimum viable product.
    • Designed multiple data- and workflow diagrams, and system architecture schemas.
    • Generated insurance certificates in PDF form, on demand, and saved the copies to S3.
    • Created a demo splash page.
    • Displayed the PDFs using Mozilla's PDF.js viewer.
    • Created two APIs, utilizing the facilities already in use by the end client, minimizing work on their side.
    • Designed and implemented data schemas, based on legal documents (insurance certificates).
    Technologies: AWS S3, PhantomJS, PDF.js, Heroku, AngularJS, Loopback, Node.js
  • Software Engineer

    2015 - 2015
    June20 (via Toptal)
    • Built a library for other developers to use, based on AngularJS.
    • Created an E2E test environment, including automated testing on iOS devices.
    • Provided automated documentation, unit tests, and demos.
    • Manually wired up advanced AngularJS functionality with reusable components, to be used by other developers.
    • Created robust workflows using Gulp, Selenium, and Browsersync.
    • Configured infrastructure on AWS (EC2, S3, IAM).
    • Communicated with and shared data to the iOS app (in a hybrid app environment).
    • Created a continuous integration and deployment environment with Travis CI.
    • Created Slack integrations.
    Technologies: PHP, Appium, iOS, Git, AngularJS, JavaScript
  • Software Engineer

    2015 - 2015
    Eyeadvise (via Toptal)
    • Improved and extended a legacy app consisting of several modules hosted on Google App Engine.
    • Fixed existing issues around the client app written in AngularJS. Added new, business-critical functionality.
    • Fixed issues around a simple Python API.
    • Created an E2E testing environment, connecting all the multiple modules and also external services.
    • Added E2E tests, created documentation, and supported the project through the development process.
    Technologies: Facebook SDK, Google App Engine, Python, AngularJS
  • Web Developer

    2007 - 2012
    • Created simple HTML-based websites.
    • Designed simple websites.
    • Developed mid-sized projects for local councils.
    • Provided a dynamic map of investment areas with detailed information, editable through Drupal CMS.
    • Supported projects and clients until they reached maturity and became stable businesses.
    Technologies: Drupal, CSS, HTML
  • Researcher/Analyst

    2007 - 2012
    Engagement Intelligence
    • Analyzed 30+ viral and marketing campaigns.
    • Performed analyses in international (English) and Scandinavian (Norwegian and Danish) territories.
    • Researched key users who have the most influence in their respective networks.
    • Worked on a variety of campaigns from entertainment (mainstream games and movies) to advanced technology projects (Windows Vista OS, Microsoft Dynamics, ASP.Net).
    • Chosen as employee of the month; delivered projects for Microsoft, Sony, Columbia Pictures, Nokia, O2, and Lionsgate among others.
  • Clinical Neuropsychologist

    2010 - 2011
    Institute of Psychiatry and Neurology, 2nd Department of Neurology
    • Designed a quantitative, clinical study based on empirical preapprehension and literature.
    • Chose adequate clinical and scientific methodology.
    • Carried out clinical and scientific research parallel to clinical duties.
    • Analyzed and measured data using chosen, sound statistical tools under supervision from a senior scientific employee.
    • Delivered a complete scientific study.
    Technologies: SPSS, Statistics, Data Science, Google Scholar


  • Professional Development and Training

    Completed several online courses in technology.

    BerkeleyX (XSeries Big Data Courses, 2015)
    - Introduction to Big Data with Apache Spark
    - Scalable Machine Learning

    BerkeleyX (Certificate Courses, 2012-2013)
    - Artificial Intelligence, Part 1
    - Software as a Service, Part 1
    - Software as a Service, Part 2

    EdX (2012-2013)
    - MongoDB for Python Developers
    - MongoDB for Node.js Developers

  • Speaker at Nomad City Conference

    Invited to give a speech at Nomad City Conference in Las Palmas de Gran Canaria, December 2016

  • Toptal Community Leader in Warsaw, Poland (2015~)

    Helped build the Toptal Community in Poland. Organized 10+ gatherings for the community in Warsaw, including two conferences. Attended Toptal gatherings in other countries. Stays in constant communication with several other leaders.

  • Webby Nominee 2015

    2015 Webby awards nominee for Nowness.com.

  • Pixel Awards Winner + People's Choice Award Winner 2015

    2015 Pixel Awards winner and People's Choice Award winner in Arts & Culture - Nowness.com

  • AngularJS State/URL Decouplement

    An invention allowing developers to change the URL without reloading the state using an AngularJS UI router.

  • High-availability Drupal App/Server + Aid Tools

    Delivered a high-availability Drupal app and server environment for the Educational Research Institute (Ministry of Education); the project was designed to allow registration of all Polish schools and also provide Microsoft Excel (VBA) tools to aid teachers.

  • LimeSurvey AngularJS Interface

    An AngularJS client for LimeSurvey, an open source survey CMS that exposed an RPC API, for a national university (Warsaw School of Life Sciences).

  • The Vital Guide to React.js Interviewing

    Article on Toptal Resources, 600+ likes.

  • AngularJS Develop Job Description Template

    Job Template for AngularJS on Toptal Resources.

  • The Vital Guide to AngularJS Interviewing
  • 11 Essential AngularJS Interview Questions
  • The 9 Most Common Mistakes That Ionic Developers Make

    Assisted in writing the article for Toptal Blog.

  • The Vital Guide to Interviewing Ethereum Developers

    The Ethereum and Solidity recruitment 101, main article under https://www.toptal.com/ethereum

  • Blockchain Development Guide

    The introduction to understanding development on distributed ledger technologies

  • Blockchain, IoT, and the Future of Transportation: Understanding the Motoro Coin (Publication)
    Open-source, IoT, and Ethereum smart contracts work together with a new utility coin to make transportation more accessible and reduce vehicle waste. In this article, Toptal Freelance Ethereum Developer Michał Mikolajczyk explains the motivations and methodology behind his startup's latest initiative.
  • Top 18 Most Common Mistakes that AngularJS Developers Make (Publication)
    AngularJS is a very powerful framework. It is the third most starred repository on GitHub. It is not difficult to start using, but the goals that it is intended to accomplish demand comprehension. No longer can we ignore memory consumption, because it will not reset on navigation anymore. This is the vanguard of web development. Let’s embrace it!
  • Toptal Mentor
    Michal is a mentor in the Toptal Global Mentor’s Program. This program is a partnership between Toptal and General Assembly to provide high quality mentorship for students from minority and low income backgrounds who are looking to begin their careers as professional software engineers. Michal shows commitment to diversity in tech by mentoring a General Assembly student every week for a year, covering everything from coding tips and tricks to advice on making it in the industry.


  • Languages

    CSS, HTML, TypeScript, SQL, ECMAScript (ES6), JavaScript, HTML5, CSS3, Solidity, GraphQL, Python, Go, PHP
  • Frameworks

    Bulma, Express.js, Jasmine, Protractor, Ionic, AngularJS, Angular, Swagger, React Native, Next.js, Material-UI, Bootstrap, Express.io, Apache Spark, Appium, Loopback, Sails.js, Flux, Redux, Linux OpenSuSe, Bootstrap 3, PhoneGap, Famo.us
  • Libraries/APIs

    AWS Amplify, REST APIs, React, Selenium WebDriver, Node.js, Facebook API, Socket.IO, Restify, D3.js, Moment.js, jQuery, Vue, Facebook SDK, PhantomJS
  • Tools

    Google Analytics, GitHub, Mocha, Gulp, Git, AWS AppSync, Amazon Cognito, Canvas, Babel, Expo.io, Auth0, Webpack, Grunt, Yeoman, React Apollo, SPSS, Travis CI, Emacs, Istio
  • Paradigms

    Unit Testing, Web Application Architecture, API Architecture, Web Architecture, RESTful Development, Continuous Integration (CI), Continuous Deployment, Test-driven Development (TDD), DevOps, Functional Programming, Agile Software Development, Scrum, Behavior-driven Development (BDD), Requirements Analysis, Data Science, Kanban, Extreme Programming, Testing, Jamstack
  • Platforms

    AWS EC2, Heroku, Amazon Web Services (AWS), Drupal, Kubernetes, Docker, Google Cloud Platform (GCP), Firebase, AWS Lambda, Blockchain, Ethereum, Linux, CentOS, Debian Linux, Google App Engine, PDF.js, iOS
  • Storage

    NoSQL, MySQL, SQL Architecture, AWS S3, AWS DynamoDB, Redis, PostgreSQL, MongoDB, Google Cloud, Elasticsearch
  • Other

    Serverless, API Applications, Web Applications, Software Architecture, Full-stack, Front-end, Back-end, Content Management Systems (CMS), UX Architecture, Code Architecture, Architecture, Styled-components, RESTful APIs, User Experience (UX), UX, Team Leadership, Technical Leadership, Task Analysis, System Architecture, Open Source, Communication, GitFlow, IT Systems Architecture, Cloud, APIs, AWS, PWA, Progressive Web Applications (PWA), Amazon Cognito User Pools, Identity & Access Management (IAM), Video Streaming, Load Balancers, Payment APIs, Minimum Viable Product (MVP), Data Architecture, Apollo, Writing & Editing, Bitcoin, DApps, Distributed Systems, Tech Conferences, Community, Coordination, Conference Speaking, Public Speaking, Team Management, Task Scheduling, Task Automation, Task Flows, Leadership, Google Material Design, Big Data, Site Reliability Engineering (SRE), Digital Currencies, ICO, Artificial Intelligence (AI), Google Scholar, Statistics, Media, Cloud Services, SVG, Cordova
  • Industry Expertise



  • Master's Degree in Neuropsychology
    2005 - 2011
    University of Warsaw - Warsaw, Poland


  • Big Data
    University of California, Berkeley | via edX
  • Scalable Machine Learning
    University of California, Berkeley | via edX
  • Introduction to Big Data with Apache Spark
    JULY 2015 - PRESENT
    University of California, Berkeley | via edX

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