Jarosław Hemmerling

Work Experience

Freelance (remote)05/2016 - present

Web Project Coordinator / Full-Stack Web Developer

Developed and extended kahawa.pl - a WooCommerce-based WordPress store - focusing on writing custom functionalities and delivering responsive feature updates.
Acted as the primary client liaison - gathering briefs, clarifying requirements, and managing feedback throughout the project lifecycle.
Collaborated with a UI Designer to implement unshade.pl from Figma mockups, translating visual designs into fully functional web pages.
Partnered with a marketing agency (stokrotka.com.pl) - consulted on creative briefs and aligned them with technical feasibility.
Served as a technical bridge between clients and the agency - translating business goals into actionable technical specifications, advising on optimal implementation paths, and proactively communicating risks and constraints.
Owned end-to-end delivery of front-end and back-end changes, ensuring all updates matched agreed specifications and were deployed on schedule.
Designed and implemented responsive email newsletters based on the Cerberus template, ensuring consistent rendering across major email clients and mobile devices.

e-file sp. z o.o. (on-site 2017 - 2019, remote since 2019)07/2017 - 09/2024

Full-Stack Developer

Designed and delivered internal technical training courses for employees from other departments.
Prototyped new features - created wireframes and mockups in Figma.
Managed a development team - responsible for task allocation, code quality, and mentoring.
Assisted with OKR planning, Sprint planning, and Product Backlog management.
Led meetings and presented features - to management and stakeholders.
Provided technical support - for business and international clients.
Wrote and maintained technical documentation - API specifications, system architecture overviews, and internal developer guides.
Created user guides and help articles - writing instructions and tutorials for end-users, published on the website to support platform navigation.
Developed and enhanced API for the Dysk e-pity product (Laravel, MySQL, Azure) - serving over 1.5 million users.
Built and maintained konto.fillup.pl - an OAuth server and account management platform (Laravel, MySQL, OAuth) handling user accounts, subscriptions, subscription-associated users, and customer support communication.
Developed and enhanced APIs - fillup, firmly (Laravel, MariaDB), and e-pity Płatnika (PHP, MSSQL).
Developed web applications - e-pity, firmly, and fillup (React, TypeScript).
Developed desktop applications - e-pity, e-pity Płatnika, and fillup (ActionScript 3, SQLite).
Developed the firmly mobile application - using Cordova, React, TypeScript, and Firebase Cloud Messaging.
Maintained and developed the odbierz-pit website - using Drupal.
Developed an alpha version of an internal tool - for signing XML files with qualified electronic signatures (C#, Ionic Zip, SecureBlackbox).
Manually tested web and desktop applications (e-pity, e-pity Płatnika, fillup, firmly).
Created and edited icons and graphics - for applications using Photoshop and Affinity Designer.

Wielkopolska Chamber of Agriculture (on-site 2014-2015, remote since 2015))04/2014 - 09/2017

Web Developer

Delivered technical training sessions - conducting workshops for employees and chamber members on IT tools and systems.
Provided IT support and equipment management - handled hardware maintenance, minor repairs, and maintained an equipment inventory log.
Built and developed a new website from scratch - including the BIP (Public Information Bulletin) subpage - using HTML5, CSS3, JavaScript, PHP, Bootstrap, and MySQL.
Managed and maintained the website - implementing changes and new features based on directives from the Board and the Director.
Acted as a liaison with regional branch managers - coordinating and publishing content for their respective regional sections.
Created graphics for the website - designed promotional materials and posters for Chamber of Agriculture elections.
Assisted with technical preparations - supporting the production of materials for General Assembly meetings.

FD Polska (stacjonarnie)05.2015 - 02.2017

Front-End Developer

Developed and maintained front-end of fastdeal.pl - implementing UI changes, bug fixes, and feature enhancements using JavaScript, jQuery, and CSS3.
Worked on both the public website and the admin panel - implementing front-end changes and minor back-end modifications (PHP, Zend Framework) to support internal workflows and content management.
Developed and maintained responsive HTML/CSS email newsletters - building and updating templates for marketing campaigns, ensuring consistent rendering across major email clients and devices.
Prepared product photos and created promotional graphics - designed banners for the website and visuals for email newsletters using Photoshop, while also managing and organizing the company's image database.
Provided technical support to non-technical staff - troubleshooting issues, assisting with software usage, and resolving day-to-day IT problems.
Used SVN for version control - managing codebase changes and collaborating with the development team.

Education

Collegium Da Vinci, Poznań (Poland)2018 - 2020

Master of Arts in Creative Management, specialization: UI Design

Collegium Da Vinci, Poznań (Poland)2014 - 2018

Bachelor of Engineering in Information Technology, specialization: Internet Technologies

Zespół Szkół Łączności (technical college), Poznań (Poland)2008 - 2012

IT Technician

Technical skills

Languages: PHP, JavaScript, TypeScript, SQL
Frameworks & Libraries: Laravel, Vue, React, Bootstrap, Tailwind
Web Technologies: HTML5, CSS3, Sass/SCSS, RESTful API, RWD, SEO, Web accessibility
Databases: MySQL, SQL Server (MSSQL), MariaDB, SQLite
Testing: PHPUnit, Jest (JS/TS)
Tools: Git, GitHub, GitLab, Figma, Postman, Swagger, Photoshop, Composer, npm, VS Code, PhpStorm
Environments: Windows, macOS, Linux, Docker

Professional skills

Client Collaboration - gathering requirements, managing feedback, and aligning technical solutions with business goals.
Leadership & Mentoring - leading development teams, conducting code reviews, and mentoring junior developers.
Communication & Documentation - technical writing (API docs, system overviews), creating user guides and help articles, cross-functional collaboration, client presentations, and stakeholder reporting.
Technical Training - designing and delivering training sessions for employees and non-technical staff.
Project Management - sprint planning, backlog management, OKR planning, and coordinating with cross-functional teams.
Problem Solving - debugging, system architecture, troubleshooting complex issues, and finding effective solutions to technical challenges.
IT Support - providing technical assistance to end-users and business clients.

Certifications

INE - eJPT (eLearnSecurity Junior Penetration Tester) - 2025

Languages

Polish - native language
English - C1

Full-Stack Developer | Product Ownership | Project Management