Mariusz Rajczakowski

Summary

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.

Certifications

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

Responsibilites:

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

Responsibilites:

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

Responsibilites:

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

Responsibilites:

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

Responsibilites:

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 https://github.com/mariocoski/rest-api-node-typescript
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 https://github.com/mariocoski/express-typescript-react-redux-universal
Blogging platform	Laravel Blogger - open source blogging platform powered by laravel 5 Technologies: laravel 5, jQuery, Scout, TinyMCE https://github.com/mariocoski/laravel-blogger
Gamechanger	Gamechanger - concrete implementation of own Laravel Blogger, blog about nutrition and healthy lifestyle https://gamechanger.mariuszrajczakowski.me
Withjavascript	WithJavaScript - concrete implementation of own Laravel Blogger, blog about javascript releated technologies https://withjavascript.mariuszrajczakowski.me

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 https://github.com/kube-js/kube-ts-server
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 https://github.com/kube-js/kube-ts-react-client
tscommons	all essential configs needed for starting new typescript application https://github.com/kube-js/tscommons
semantic-release	semantic release scripts for different CI services https://github.com/kube-js/semantic-release
renovate-config	shareable config presets for js apps/libraries https://github.com/kube-js/renovate-config
kube-ts-chart	basic chart for setting up kube-ts-* applications on kubernetes cluster https://github.com/kube-js/kube-ts-chart

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 https://github.com/js-items/foundation
knex	concrete implementation of js-items for knex.js query builder https://github.com/js-items/knex
express	concrete implementation of js-items for express https://github.com/js-items/express
ky	concrete implementation of js-items for ky https://github.com/js-items/ky

Education

2009-2012

Bachelor of Science in Dietetics

Medical University, Wroclaw, Poland

2006-2011

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

University of Environmental and Life Science, Wroclaw, Poland

Languages

English - full working proficiency
Polish - native
German - basic