Mariusz
From Poland (GMT+2)
10 years of commercial experience
Lemon.io stats
2
projects done966
hours workedOpen
to new offersMariusz – 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
Additional skills
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Potentially possibleExperience Highlights
Senior Full-Stack Engineer
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.
- 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.
Lead Software Engineer
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.
- 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.
Senior JavaScript Engineer
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.
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;
Software Engineer
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.
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.
Web Developer
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.
- 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