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Krzysztof Czernek
Verified Expert in Engineering
Full-stack Developer
Kraków, Poland
Toptal member since February 19, 2019
Bio
Krzysztof is a product-minded, full-stack developer with several years of experience, collaborating directly with startup founders and CEOs to bring their ideas to life and work on projects for Fortune 500 companies. He is passionate about lean product development and consulting. Thanks to his technical expertise, business focus, and ability to communicate in a clear and reasoned fashion, Krzysztof is a great partner for brainstorming ideas and delivering incredible products.
Portfolio
Deliveroo
JavaScript, TypeScript, React, Ruby, Ruby on Rails (RoR), Go, Terraform...
Pfizer
TypeScript, JavaScript, React, Node.js, PostgreSQL, Git, Docker, CSS...
Iterate Labs (via Toptal)
JetBrains IDE, MacOS, REST, Lean Startups, Business Requirements...
Experience
- SQL - 9 years
- Ruby on Rails (RoR) - 9 years
- Agile Software Development - 9 years
- React - 6 years
- Node.js - 6 years
- JavaScript - 6 years
- Software Consulting - 6 years
Preferred Environment
Amazon Web Services (AWS), Slack, Google Chrome, JetBrains IDE, GitHub, Git, Bash, MacOS, Agile
The most amazing...
...algorithm I've created analyzed meteorological phenomena areas and their impact on flight routes.
Work Experience
Senior Software Engineer
2021 - PRESENT
Deliveroo
- Worked as a full-stack developer in a platform engineering team.
- Maintained and improved an internal release management application used by hundreds of engineers daily. Helped rewrite the front end of the application, introducing a new design and refactoring a big part of the codebase.
- Contributed to various elements of the development tooling ecosystem across the organization.
Technologies: JavaScript, TypeScript, React, Ruby, Ruby on Rails (RoR), Go, Terraform, Amazon Web Services (AWS), PostgreSQL, Docker, CircleCI, Git, CSS, GraphQL, Architecture, Front-end, Back-end
Tech Lead | Full Stack Developer
2020 - 2021
Pfizer
- Led a distributed front-end development team of three people to create, from the ground up, a modern collaborative platform to replace the Excel-based processes of an internal team.
- Contributed to the back-end development, database design, cloud architecture, and deployment processes and practices for the whole project.
- Delivered the first MVP, from design specs to regular production deployments, in under three months.
- Collaborated with business owners, designers, and technical stakeholders in defining requirements and designs.
Technologies: TypeScript, JavaScript, React, Node.js, PostgreSQL, Git, Docker, CSS, Architecture, Leadership, Front-end, Back-end, Next.js
Lead Software Engineer
2020 - 2020
Iterate Labs (via Toptal)
- Maintained, improved, and scaled an AWS-based infrastructure for a real-time IoT data processing system of 1000s of events per second.
- Designed and conducted end-to-end tests of the full data pipeline prior to production release.
- Implemented and deployed admin applications for end users and back office administration of the system.
- Implemented monitoring, alerting, data retention policies, and performance improvements across critical systems.
- Collaborated with the in-house data science team on integrating data processing models into the system.
Technologies: JetBrains IDE, MacOS, REST, Lean Startups, Business Requirements, Team Leadership, System Architecture, IT Consulting, ECMAScript (ES6), Consulting, Lean Product Development, Technical Leadership, APIs, GitHub, Algorithms, Amazon Kinesis, AWS Lambda, Ruby on Rails 5, Amazon S3 (AWS S3), Amazon EC2, Ruby, Bash, Software Consulting, Agile Software Development, Agile, Git, Amazon Web Services (AWS), Full-stack, Kubernetes, Docker, PostgreSQL, SQL, JavaScript, React, Ruby on Rails (RoR), CSS, Architecture, Leadership, Front-end, Back-end
Tech Lead | Full-stack Developer | Consultant
2013 - 2020
u2i
- Maintained a mobile app, developed a data processing pipeline and helped with data migration from on-premise to the cloud in a healthcare institution.
- Created a service for correlating data from disparate sources with a reference database of hundreds of millions of records.
- Worked directly with a founder to take the idea from conception to a working prototype.
- Created a collaborative platform for municipal governments from the ground up while working directly with a startup's CEO.
- Helped multiple clients refine their ideas and develop plans for prototypes and MVPs.
- Advised clients on technology, product development, and lean practices.
- Helped find new clients, took an active part in early sales interactions, and contributed to writing proposals.
- Ran workshops on JavaScript, functional programming, and organized hackathons.
- Helped design and implement the recruitment process for junior, mid, and senior developers and conducted interviews.
- Helped streamline the transition to remote work, developed internal tools, and improved internal processes.
Technologies: JetBrains IDE, HIPAA Compliance, Functional Programming, MacOS, REST, Business Consulting, Semantic UI, Lean Startups, Business Requirements, Team Leadership, System Architecture, IT Consulting, ECMAScript (ES6), Consulting, Lean Product Development, Technical Leadership, APIs, GitHub, Algorithms, React Native, PostgreSQL, AWS Lambda, RxJS, TypeScript, Amazon S3 (AWS S3), Amazon EC2, MySQL, Bash, Software Consulting, Express.js, Redux, Agile Software Development, Agile, Amazon Web Services (AWS), Full-stack, Git, Terraform, Docker, SQL, Flask, Ruby on Rails (RoR), Node.js, React, Python, Ruby, JavaScript, CSS, Architecture, Leadership, Front-end, Back-end, Next.js
Software Engineer Intern
2013 - 2013
Smart4Aviation
- Worked on algorithmic solutions to area related problems.
- Analyzed meteorological phenomena and their impact on flight routes.
- Mentioned in an errata for finding a mathematical mistake in "Some Algorithms for Polygons on a Sphere" by Robert G. Chamberlain and William H. Duquette (NASA Jet Propulsion Laboratory).
Technologies: Algorithms, Java, Back-end
Software Engineer
2013 - 2013
Schibsted Tech Polska
- Built an iPhone application for sports statistics from the ground up, in two months, with no prior experience with iOS and Objective-C.
Technologies: JetBrains IDE, MacOS, APIs, GitHub, Bash, Agile Software Development, Agile, Git, SQL, Full-stack, Java, Objective-C, Back-end
Experience
Release Management Application
Internal release management application used by hundreds of engineers daily.
I handled the full-stack development, executed a major web application redesign, and introduced improvements to the release management process across the organization.
Technologies: JavaScript, TypeScript, React, Ruby on Rails, Docker, AWS, Terraform, Go, CircleCI
I handled the full-stack development, executed a major web application redesign, and introduced improvements to the release management process across the organization.
Technologies: JavaScript, TypeScript, React, Ruby on Rails, Docker, AWS, Terraform, Go, CircleCI
Data Processing Pipeline and Mobile App | Healthcare
I handled the full-stack development of a data processing pipeline and maintenance of a cross-platform mobile app in the healthcare space along with the migration from on-premise to a cloud-based infrastructure.
I took an active part in all stages of the project: from proposals and defining requirements to technical strategy planning and hands-on full-stack development. I also worked in a team of four developers for over a year.
• Client's review: https://clutch.co/profile/u2i#review-1392252
Technologies: Python, JavaScript, Flask, Apache Airflow, React Native, React, Docker, Terraform, AWS
I took an active part in all stages of the project: from proposals and defining requirements to technical strategy planning and hands-on full-stack development. I also worked in a team of four developers for over a year.
• Client's review: https://clutch.co/profile/u2i#review-1392252
Technologies: Python, JavaScript, Flask, Apache Airflow, React Native, React, Docker, Terraform, AWS
Data-matching Service
A service for correlating data from disparate sources with a reference database of hundreds of millions of records, heavily utilizing string similarity algorithms. This is a mission-critical system that's been running in production for over two years now with minimal maintenance and support required.
I handled the full-stack development and architecture design from the ground up. I worked in a team of two developers for nine months.
Technologies: Ruby, Ruby on Rails, MySQL, Terraform, Chef, Capistrano
I handled the full-stack development and architecture design from the ground up. I worked in a team of two developers for nine months.
Technologies: Ruby, Ruby on Rails, MySQL, Terraform, Chef, Capistrano
Citymart Opportunity Builder
A collaborative platform for municipal governments to streamline and improve procurement processes.
I handled the full-stack development and architecture design from the ground up and for two years, I worked in a team of 2-4 developers.
• Review: https://clutch.co/profile/u2i#review-409571
Technologies: JavaScript, React, Redux, RxJS, Webpack, Jest, Node.js, Python, Flask, PostgreSQL, Docker, Terraform, AWS
I handled the full-stack development and architecture design from the ground up and for two years, I worked in a team of 2-4 developers.
• Review: https://clutch.co/profile/u2i#review-409571
Technologies: JavaScript, React, Redux, RxJS, Webpack, Jest, Node.js, Python, Flask, PostgreSQL, Docker, Terraform, AWS
Personal Knowledge Management System
A prototype for a personal knowledge management system to help business people better manage their information.
I handled the full-stack development and architecture design from the ground up. I worked in a team of two developers for six months.
Review: https://clutch.co/profile/u2i#review-764612
Technologies: JavaScript, TypeScript, React, Redux, RxJS, Webpack, Jest, Node.js, Neo4j, Docker
I handled the full-stack development and architecture design from the ground up. I worked in a team of two developers for six months.
Review: https://clutch.co/profile/u2i#review-764612
Technologies: JavaScript, TypeScript, React, Redux, RxJS, Webpack, Jest, Node.js, Neo4j, Docker
Articles on Functional Programming in JavaScript
A series of articles on functional programming in JavaScript. It was published in DailyJS on Medium.
Articles on Consulting and Lean for Software Developers
A series of articles on Consulting and Lean for Software Developers. It was published in Hacker Noon at Medium.
Education
2011 - 2015
Bachelor of Engineering Degree in Computer Science
AGH University of Science and Technology - Kraków, Poland
Skills
Libraries/APIs
Node.js, React, RxJS
Tools
GitHub, Git, Terraform, CircleCI
Languages
JavaScript, ECMAScript (ES6), SQL, TypeScript, Bash, Ruby, HTML, Objective-C, Java, Python, Go, CSS, GraphQL
Frameworks
Redux, Express.js, Material UI, Jest, Ruby on Rails 5, Ruby on Rails (RoR), React Native, Next.js, Flask
Paradigms
Agile, Agile Software Development, REST, Functional Programming, HIPAA Compliance
Platforms
Amazon Web Services (AWS), Docker, Amazon EC2, AWS Lambda, MacOS, Kubernetes, Firebase
Storage
Amazon S3 (AWS S3), PostgreSQL, MySQL
Other
Technical Leadership, Full-stack, APIs, Lean Product Development, Consulting, Architecture, Leadership, Front-end, Back-end, Software Consulting, Team Leadership, System Architecture, Business Requirements, Algorithms, Lean Startups, IT Consulting, Business Consulting, Semantic UI, SaaS, Amazon Kinesis, JetBrains IDE
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