Patryk is available for hire
Hire PatrykPatryk Siemiński
Verified Expert in Engineering
Software Developer
Location
Szczecin, Poland
Toptal Member Since
February 22, 2022
Patryk is a full-stack software engineer with broad experience in eCommerce, always open for challenges in various industries, be it intellectual property or airport awareness applications. He treats programming languages as tools to achieve business goals and believes that product discovery and domain knowledge are as important as software engineering skills. Patryk has experience working with startups and corporations providing SaaS platforms.
Portfolio
Carla
Go, Enterprise, GraphQL, PostgreSQL, Google Cloud Platform (GCP), Encore...
Siili
Java, Spring, Spring Boot, Git, Jira, PostgreSQL, MongoDB, Redis, REST...
Pierce Group
Java, Spring, Spring Boot, Apache Kafka, Solr, Git, Oracle Database, eCommerce...
Experience
Availability
Part-time
Preferred Environment
Slack, IntelliJ IDEA, Jira, Git, Scrum, MacOS, Windows
The most amazing...
...thing I've done is the development of a web-based eCommerce platform that is used by over 6,500 online stores.
Work Experience
Senior Software Engineer
2022 - 2023
Carla
- Led the transition of infrastructure to GCP and Encore.dev as part of the platform team. Reduced time dedicated to infrastructure management and product delivery by over 90% thanks to the automated processes.
- Automated and simplified car publishing process. Lowered the average time of publishing by 69% for Carla online store and 86% for Blocket ads, with 71% for total time saved, significantly reducing error rate and update time.
- Introduced new fully automated integrations with advertising platforms, cutting the average time to publish a batch of external adverts from 1-2 working days to 1 hour.
Technologies: Go, Enterprise, GraphQL, PostgreSQL, Google Cloud Platform (GCP), Encore, Graph Query Language (GQL), Gin-Gonic, TypeScript, JavaScript, React, REST, REST APIs, Pub/Sub, Git, ECMAScript (ES6), Web Applications, Unit Testing, Test-driven Development (TDD), Event-driven Architecture, Code Review, Docker, Kubernetes, Message Queues, SQL, Full-stack
Senior Full-stack Engineer
2021 - 2022
Siili
- Oversaw the product discovery phase and planned and delivered a subproject for the airport awareness system app. Communicated with the client and external providers.
- Reviewed the product increments with the client to ensure that the expected value was delivered on time with a tight project schedule.
- Led the project team and ensured obstacles-free work. Mentored less experienced back- and front-end engineers and worked together executing pair programming.
- Gathered requirements and designed the integration of new back-end services into the existing distributed system.
- Developed and implemented a new module in React and React Native for Android and iOS mobile as the leading front-end developer in the project.
- Accelerated refactoring of older modules to modern React hooks API.
Technologies: Java, Spring, Spring Boot, Git, Jira, PostgreSQL, MongoDB, Redis, REST, REST APIs, RESTful Microservices, JMS, Pub/Sub, JavaScript, TypeScript, React, Redux, Redux-Saga, React Native, Google Cloud Platform (GCP), Docker, Kubernetes, Unit Testing, Jest, Amazon Web Services (AWS), GitHub, APIs, Full-stack, Code Review, Microservices, Spring Microservice, Domain-driven Design (DDD), Message Queues, Event-driven Architecture, Test-driven Development (TDD), JUnit, Full-stack Development, SQL, HTML, HTML5, ECMAScript (ES6), CSS3, Front-end, GraphQL, Application State Management, Storybook, Hibernate, Front-end Development, Web Applications, Sass, Figma, React Redux, Mockito
Senior Java Software Engineer
2019 - 2021
Pierce Group
- Led the back end implementation of the new discounts and campaigns module with kick-off during the 2020 Black Friday campaign, which led to time savings for marketing and pricing departments and conversion growth.
- Refactored and improved functionality to match complex combinations of bundled products with customers' motorbikes, leading to better conversions and a lower number of returns caused by a mismatch of bought parts.
- Introduced new integrations with payment providers like Adyen and Klarna, enabling the company to grow in new international markets.
- Participated in support rotations, dealing with weekly telephone support queries after working overtime and the night shift during critical periods, like Black Friday.
- Mentored new back-end engineers in my team and worked together executing pair programming.
Technologies: Java, Spring, Spring Boot, Apache Kafka, Solr, Git, Oracle Database, eCommerce, Microsoft SQL Server, Docker, Jenkins, GitHub, APIs, Code Review, REST, REST APIs, Microservices, Spring Microservice, RESTful Microservices, Message Queues, Test-driven Development (TDD), JUnit, Unit Testing, Back-end Development, SQL, Hibernate, Web Applications, Mockito
Senior Full-stack Engineer
2018 - 2019
IAMIP Sverige
- Accelerated growth of functionalities in company products during the intensive period of the startup lifecycle, which led to the company obtaining many new valuable customers and enterprise subscriptions.
- Developed new features and maintained the existing codebase in multiple microservices of an intellectual property app created by startups and used by hundreds of the world's most innovative companies.
- Improved and added new capabilities to the app search language for intellectual property database, holding data of millions of patents worldwide.
- Upgraded the codebase by introducing good practices like TDD, layered architecture, and elements of DDD, which led to quality improvement of the code and faster iterations for new features and enhancements in the product.
- Refactored the React and Redux app to recently released hooks API.
Technologies: Git, Elasticsearch, Amazon Web Services (AWS), CSS, PHP, JavaScript, TypeScript, RabbitMQ, React, Redux, Redux-Saga, MongoDB, Docker, Unit Testing, Jest, GitHub, GitLab, APIs, Code Review, Full-stack, PHPUnit, Styled-components, Microservices, RESTful Microservices, REST, REST APIs, Test-driven Development (TDD), Full-stack Development, Jira, SQL, HTML5, ECMAScript (ES6), HTML, CSS3, Front-end, Application State Management, Front-end Development, Web Applications, Sass, React Redux
Full-stack Engineer
2017 - 2018
Squiz
- Developed and maintained projects for a UK branch in CRM systems.
- Improved functionalities of automatic email content parsing and categorization for further processing and collaboration by platform end-users.
- Collaborated with a distributed team in the UK and Poland to deliver successful projects created for customers from London.
Technologies: PHP, JavaScript, MySQL, Elasticsearch, Git, CSS, HTML, SQL, Full-stack, Full-stack Development, Trello, MacOS, Front-end, Front-end Development, Web Applications
Full-stack Engineer
2015 - 2017
IdoSell
- Led the development of a new service, collecting and presenting discounts and campaigns from thousands of stores running on the IdoSell platform.
- Developed and maintained the IdoSell platform used by thousands of stores globally.
- Implemented or improved various integrations with external systems like PayPal, eBay, and Allegro.
- Refactored legacy admin application for online store platform to align with modern UI/UX designs, using JavaScript components, SASS, and CSS.
Technologies: Git, PHP, MySQL, Memcached, JavaScript, jQuery, SlimPHP, eCommerce, CSS, HTML, Bitbucket, SQL, Full-stack, Full-stack Development, APIs, REST, REST APIs, CSS3, Front-end, Front-end Development, Web Applications
Experience
Airport Operational Status | AOS
https://www.siili.com/finavia-situational-awareness-solution-for-airportsA web-based app as a situational awareness solution for airports. As the full-stack engineer, I distributed Java and Spring framework microservices on the back end and TypeScript, React, and React Native for the client browser and mobile applications.
The application was cloud-enabled, using distributed microservices connected asynchronously by queues. Used caching extensively to improve end-user experience. Fully Dockerized with automatic Kubernetes cluster deployments.
The application was cloud-enabled, using distributed microservices connected asynchronously by queues. Used caching extensively to improve end-user experience. Fully Dockerized with automatic Kubernetes cluster deployments.
Pierce Group Online Stores
https://www.24mx.co.uk/A web application backed by microservices as a network of online stores owned by the Pierce Group. As a back-end engineer, I worked on multiple integrations, payment providers, product and motorbike matching solutions, new campaigns, and discount engines used for Black Friday.
The platform and microservices were written in Java with the Spring framework connected by Apache Kafka, backed by Microsoft SQL database.
The platform and microservices were written in Java with the Spring framework connected by Apache Kafka, backed by Microsoft SQL database.
IamIP | Patent platform
https://iamip.com/A PHP and TypeScript-based web app for patents and intellectual property search. Collaboration and management for innovative tech companies and trademark attorneys. I was the full-stack engineer engaged in back-end microservices, automated integration with global data providers, and front-end applications used by the lawyers and employees of engineering departments.
Distributed PHP microservices with MySQL databases weren't the only challenge I faced. A high-performing and automatic integration with globally distributed patent offices, authorities, and providers were at the base of the platform. With over 100 million individual patents and 100,000 or more added every week, held in MongoDB and Elasticsearch to provide quick and complex searching capabilities.
On the front end, multiple collaboration functionalities were implemented with React, Redux, and Redux-saga.
Distributed PHP microservices with MySQL databases weren't the only challenge I faced. A high-performing and automatic integration with globally distributed patent offices, authorities, and providers were at the base of the platform. With over 100 million individual patents and 100,000 or more added every week, held in MongoDB and Elasticsearch to provide quick and complex searching capabilities.
On the front end, multiple collaboration functionalities were implemented with React, Redux, and Redux-saga.
IdoSell | Online Store Platform
https://www.idosell.com/en/A PHP and JavaScript-based SaaS platform used by more than 6,500 unique online stores of varying scale and traffic. As part of my role, I improved and implemented new features, SQL queries optimization, and multiple integrations with external services, including PayPal, eBay, and many global delivery providers.
I've worked on internal tools used by web design teams to accelerate the delivery of unique store templates tailored to the client's needs.
I've worked on internal tools used by web design teams to accelerate the delivery of unique store templates tailored to the client's needs.
Skills
Languages
Java, SQL, TypeScript, PHP, JavaScript, CSS, HTML, HTML5, ECMAScript (ES6), CSS3, Go, SCSS, XML, XLST, GraphQL, Sass
Libraries/APIs
React, REST APIs, Redux-Saga, React Redux, jQuery, JMS
Paradigms
Object-oriented Programming (OOP), REST, Scrum, Unit Testing, Event-driven Architecture, Test-driven Development (TDD), Microservices
Other
eCommerce, Back-end Development, Full-stack Development, Full-stack, Code Review, Web Applications, APIs, Domain-driven Design (DDD), Message Queues, Front-end, Front-end Development, RESTful Microservices, Pub/Sub, Styled-components, Application State Management, Storybook, Enterprise, Encore, Graph Query Language (GQL)
Frameworks
Spring, Spring Boot, Redux, Symfony, PHPUnit, JUnit, Hibernate, Mockito, React Native, Jest, Spring Microservice, Gin-Gonic
Tools
Git, IntelliJ IDEA, Jira, RabbitMQ, Solr, Slack, Jenkins, Docker Compose, GitHub, GitLab, Bitbucket, Trello, Figma
Platforms
MacOS, Linux, Apache Kafka, Oracle Database, Windows, Docker, Google Cloud Platform (GCP), Kubernetes, Percona, Amazon Web Services (AWS)
Storage
NoSQL, MySQL, PostgreSQL, JSON, MongoDB, Memcached, Redis, Elasticsearch, Microsoft SQL Server, SlimPHP
Education
2012 - 2016
Bachelor's Degree in Computer Science
West Pomeranian University of Technology in Szczecin - Szczecin, Poland
Certifications
DECEMBER 2021 - DECEMBER 2024
AWS Certified Solutions Architect | Associate
Amazon Web Services
DECEMBER 2021 - DECEMBER 2024
AWS Certified Developer | Associate
Amazon Web Services
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