Mariusz Rajczakowski

Hi there!

My name is Mariusz Rajczakowski

I'm a Senior Software Engineer and AWS Certified Solutions Architect based in Milton Keynes, UK.

I focus on JavaScript / TypeScript, Docker, Kubernetes, Terraform, AWS cloud.


I specialise in JavaScript / TypeScript, using React.js and Node.js on a daily basis. I bring DevOps mindset into organisations, providing various automation solutions to make systems more secure, reliable, save time and money.

I am experienced in building complex web applications including single page applications, APIs, setting up CI/CD pipelines and infrastructure.

I am AWS Certified Solutions Architect - Associate and I use many of AWS services on daily basis. I like using terraform to scaffold my infrastracture and maintain reproducible environments.

I am not afraid to take a lead, having had experience in managing other software engineers, providing expertise and mentorship when required.

I have outstanding verbal/written communication skills and able to translate client's requiements into simple, secure, reliable and cost-effective technical solutions.


Amazon Web Services Solutions Architect Associate

Issued March 2020 - Expires March 2023

Credential ID: MM9TWP32M2EQ1NCQ

Core technologies

Cloud Amazon Web Services (AWS), Digital Ocean
AWS services VPC, EC2, ELB, S3, CloudFront, EKS, ECS, ECR, Lambda, API Gateway, RDS, Route53, CloudFormation, ElastiCache, Elasticsearch Service
Infrastructure as code Terraform, CloudFormation
CI/CD CircleCI, Jenkins
Containers and VMs Docker, VirtualBox
Containers orchestration Kubernetes, docker-swarm, docker-compose
Monitoring services Datadog, Loggly, EFK
Front-end JavaScript/Typescript, React.js, Vue.js
Back-end Node.js/Express.js, php/Laravel 5
Databases MySQL, MongoDB
Other data stores ElasticSearch, Redis
Operating Systems Linux, MacOS, Windows

Professional experience

Senior JavaScript Engineer
5App Limited
September 2019 - Present
London, United Kingdom


  • implemented new features of LMS (Learning Management System) using technologies: react.js, react-router v5, flux, node.js, jest, mysql, redis, docker, docker-compose, docker-swarm
  • created and maintained microservices
  • architected solutions using AWS services
  • maintained terraform scripts
  • created and maintained CI/CD pipelines in circleci and Jenkins
  • was responsible for interviewing and hiring software engineers

Senior JavaScript Engineer
Slate Apps Limited
June 2018 - September 2019
Swindon, United Kingdom


  • worked on first market mortgage product for over 55s from service design/incubation to live in 10 months at our client Nationwide Building Society recognised already by Financial Times
  • developed several features of mortgage application (single page application), using react.js, react-router v4, Context API, signalR, axios, formik, semantic-ui, NBS-UI library, jest
  • worked effectively with UI/UX designers producing high quality prototypes using storybook and invision
  • created and maintained shared components and themes of internal UI library (NBS-UI), using react.js, semantic-ui, storybook, jest
  • helped develop node.js CLI tool to speeds up BDD testing
  • assisted in Jenkins pipelines setup, maintained and monitored kubernetes resources (microservices) using EFK stack
  • worked in cooperation with .NET engineers pioneering implementation of Event Driven Architecture at Nationwide Building Society
  • mentored TDP (Technology Development Programme) graduates enabling them gain real-world experience

Software Engineer
HT2Labs Limited
January 2017 - June 2018
Oxford, United Kingdom


  • developed and maintained GDPR application, which allowed our clients stay compliant with EU law regulations. I used the following technologies: typescript, react.js, node.js, mysql, parcel, react-semantic-ui
  • developed and maintained Learning Locker (learning record store) using technologies: react.js, redux, node.js, redis, mongo, webpack, twitter bootstrap 3
  • developed and maintained Red Panda - e-learning hub using different technologies: laravel 5, vue.js, mysql, elasticsearch, webpack, gulp, twitter bootstrap 3
  • built a full-text search solution based on elasticsearch for surfacing Red Panda hub
  • mentored and managed other developers

Software Developer
Space and Time Limited
November 2015 - January 2017
Reigate, United Kingdom


  • assisted with rebuilding data broker platform RefreshedDirect (Experian - data source) using technologies: laravel 5,vue.js, react.js, mysql, semantic UI
  • created multi-threaded CLI tool in java to import 16GB csv files (Experian data) into database
  • built and maintained internal Facebook Ad Booking Platform using technologies: laravel 5, angular.js, semantic UI, facebook API
  • maintained ad url tagging platform for various clients using technologies: laravel 5, angular.js, semantic UI
  • created and maintained adverts’ reports pages for different clients using technologies: laravel 5, vue.js, semantic UI, Google API, Bing API
  • maintained and configured servers (Digital Ocean, OVH)

Junior Web Developer
Rock Insurance Services Limited
August 2015 - November 2015
Crawley, United Kingdom


  • created CLI tool to replace manual process of processing our client gift card codes using technologies: C# + .NET, MSSQL
  • white labeled travel insurance websites for various clients using technologies: C# and .NET, MSSQL, knockout.js, twitter bootstrap 3, Windows Server
  • designed and maintained email templates for various clients using technologies: HTML, CSS, pure 360

I ❤️ Open Source

Personal projects

RESTful api RESTful api providing foundation for a blogging platform
Technologies: typescript, node.js, express.js, jest, JWT, Sequelize
Universal app Universal project (with server side rendering, code splitting and hot module reloading) which allows you to quickly get up and going with any large scale javascript app
Technologies: typescript, react.js, redux, node.js, express.js, jest, JWT, Sequelize
Blogging platform Laravel Blogger - open source blogging platform powered by laravel 5
Technologies: laravel 5, jQuery, Scout, TinyMCE
Gamechanger Gamechanger - concrete implementation of own Laravel Blogger, blog about nutrition and healthy lifestyle
Withjavascript WithJavaScript - concrete implementation of own Laravel Blogger, blog about javascript releated technologies

Github organisations

I created kube-js organisation with 6 projects, implementing CI/CD pipelines with CircleCI and automated processes: build, lint, duplication check, semantic release and deployment.

kube-ts-server dockerized restful API ready to be deployed on kubernetes cluster
Technologies: typescript, node.js, express.js, jest, JWT, helm, kubernetes, docker, CircleCI
kube-ts-client dockerized single page application ready to be deployed on kubernetes cluster
Technologies: typescript, react.js, jest, formik, i18n, react-router v5, redux, redux-saga, helm, kubernetes, docker, CircleCI
tscommons all essential configs needed for starting new typescript application
semantic-release semantic release scripts for different CI services
renovate-config shareable config presets for js apps/libraries
kube-ts-chart basic chart for setting up kube-ts-* applications on kubernetes cluster

I created js-items organisation with 4 projects, implementing CI/CD pipelines with CircleCI and automated processes: build, lint, checking duplication, semantic release and deployment.

foundation provides a set of interfaces and tests for concrete implementations of js-items repositories
knex concrete implementation of js-items for knex.js query builder
express concrete implementation of js-items for express
ky concrete implementation of js-items for ky



Bachelor of Science in Dietetics

Medical University, Wroclaw, Poland


Bachelor of Science & Master of Science in Food Technology and Human Nutrition

University of Environmental and Life Science, Wroclaw, Poland


  • English - full working proficiency
  • Polish - native
  • German - basic