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Mariusz – Node.js, React, Typescript, experts in Lemon.io

Mariusz

From Poland (GMT+2)

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Full-stack Web DeveloperSenior
DevOpsMiddle-to-senior
Hire developer
9 years of commercial experience
Banking
Business intelligence
Design
Environmental services
Healthcare
Legal tech
Marketing
Collaboration tools
Mobile apps
Platforms
Lemon.io stats
2
projects done
966
hours worked
Open
to new offers

Mariusz – Node.js, React, Typescript

Mariusz is a Senior Full-stack Developer with extensive expertise in JavaScript, React, TypeScript, and Node.js. He possesses deep analytical thinking and problem-solving skills, with a thorough understanding of how JavaScript works under the hood. Mariusz stays updated with the latest JavaScript features and is highly recommended for his ability to mentor less experienced developers. In the DevOps domain, Mariusz demonstrates strong proficiency in CI/CD, GitOps, AWS, and Docker. Mariusz excels in communicating complex concepts in simple terms, making him effective in customer interactions. He is always happy to help and exchange knowledge in open repository communities.

Main technologies
Node.js
6.5 years
React
6.5 years
Typescript
6 years
Terraform
4 years
JavaScript
7.5 years
AWS
5 years
Kubernetes
4 years
CI/CD
5 years
Additional skills
Docker
GCP
REST API
GraphQL
Jenkins
Cloud Architecture
Knex.js
PostgreSQL
Express.js
Web Sockets
Jest
Terraform
Kafka
NX
Datadog
Formik
Semantic UI
OAuth
Storybook
WebSocket
GitHub Actions
Amazon S3
Prisma
Redis
Java
Firebase
Amazon CloudFront
Next.js
Nest.js
MongoDB
Vercel
Ready to start
ASAP
Direct hire
Potentially possible

Experience Highlights

Senior Full-Stack Engineer
Jan 2022 - Jul 20226 months
Project Overview

Sourceful is an all-in-one platform that helps users create more sustainable packaging quickly and at scale. It is possible to design the packaging online in minutes or together with experts to develop a bespoke solution.

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Responsibilities:
  • Suggested merge of the self-service app with auto stock background processes into a single system called stock-management system as addressed the same client need: "making sure that client will not run out of stock at their location";
  • Created a Front-End and Back-End architecture;
  • Dockerized solution for local development and deployment to Kubernetes cluster;
  • Created a Front-End single-page application using React.js, TypeScript, 0Auth, and Hooks by using "screaming" architecture;
  • Created microservice TypeCcript & Node.js template to be used across following DDD and hexagonal architecture with highly decoupled code by following best practices;
  • Added DB integration tests to test the working solution thoroughly;
  • Implemented own Graphql server using apollo Graphql + Nexus + Data loader for efficient data querying;
  • Integrated with a variety of APIs, including 0Auth management API, Gcloud services (PubSub, Google Storage), emailService & SendGrid
  • Wrote unit and integration tests;
  • Set up Google topics and "Dead letter" topics and tuned the async communication configuration.
Project Tech stack:
Kubernetes
Node.js
GitHub Actions
JavaScript
Docker
PostgreSQL
Apollo GraphQL
Knex.js
Express.js
Cloud Architecture
OAuth
Typescript
React
Lead Software Engineer
Mar 2021 - Dec 20218 months
Project Overview

Proximie is a technology platform that allows clinicians to virtually ‘scrub in’ to any operating room or cath lab from anywhere in the world. The target audience is surgeons, hospital coordinators, health professionals, and medical students. The app consists of 2 client-facing single-page apps: the dashboard app and the live app.

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Responsibilities:
  • Was responsible for leading a "dashboard" team of 6 software engineers to deliver the solution;
  • Helped to grow the team members, organized show & tell sessions and OKRs reviews;
  • Implemented an 0Auth invite-only flow integration and turned off the standard registration as only hospitals and unis were allowed to invite trusted users;
  • Implemented 0Authauth management API integration to allow managing users and organizations;
  • Wrote unit & integration tests;
  • Implemented cypress e2e tests, including 0Auth login flow + user journeys;
  • Improved Devex, including local development: DB seeds, CLI commands, and debugging solutions.

Main achievement:

  • As this industry was highly regulated by HIPAA compliant, data had to be stored in the location where the existing session/organization, so Mariusz was involved in designing multi-region data center architecture for providing a de-identified data storage solution - imagine a central server hosting non-PII in central location and store reference to data in data stores in satellite locations, the challenge was to marry up those data in the dashboard and get accurate PII in the runtime performance, and fallbacks.
Project Tech stack:
Node.js
PostgreSQL
AWS
WebRTC
Web Sockets
Docker
Terraform
React
Typescript
OAuth
Cypress
Senior JavaScript Engineer
Jun 2018 - Sep 20191 year 3 months
Project Overview

Nationwide Building Society is a building society owned by its members. Anyone who banks, saves, or has a mortgage with them. They run for members' benefit and help the communities around them. The app Mariusz worked under was for mortgage brokers to make the process of streamlining mortgages easier, including all its stages and integration with banking services using event-driven architecture.

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Responsibilities:

Main responsibilities:

  • 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 invasion;
  • 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 speed up BDD testing;
  • Assisted in Jenkins pipelines setup, maintained and monitored Kubernetes microservices using EFK stack;
  • Worked in cooperation with .NET engineers pioneering implementation of Event Driven Architecture at Nationwide Building Society;
  • Mentored Technology Development Programme graduates, enabling them to gain real-world experience.
  • Worked on C#/.net microservices (affordability-checker, eligibility-checker, message-service, api gateway)

Main accomplishment:

  • Worked on first market mortgage product for over 55s from service design to live in 10 months;
Project Tech stack:
Jest
Terraform
Kafka
Semantic UI
NBS library
Jenkins
Kubernetes
Node.js
SignalR
Formik
React
Storybook.js
Datadog
Software Engineer
Jan 2018 - Jun 20185 months
Project Overview

HT2Labs help learning and development get brighter through data. Mariusz developed and maintained the GDPR application, which allowed clients to stay compliant with EU law regulations.

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Responsibilities:

Main tasks:

  • Created front-end and backend architecture;
  • Dockerized solution;
  • Implemented CI/CD pipelines;
  • Set up infrastructure including MYSQL DB;
  • Wrote unit, integration, and e2e tests.
Project Tech stack:
Node.js
Typescript
MySQL
React
Semantic UI
Parcel
Web Developer
Nov 2015 - Jan 20171 year 2 months
Project Overview

Mariusz has created a multi-threaded CLI tool in Java to import 16GB CSV files (Experian data) into a local database used for marketing purposes.

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Responsibilities:
  • Implemented CLI app using java and 4 threads concurrency;
  • Designed and implemented DB schema (migrations)
  • Maintained the app over time according to the new requirements
Project Tech stack:
Java
MySQL

Education

2011
Food Technology and Human Nutrition
Master's degree

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