Jens O.-Senior UX Engineer · UI Libraries · Design Systems · Server-Side Rendering
Check rate
Experience
Frontend Developer
Volkswagen Financial Services AG
Cross-brand design system
Focus: Analysis of the causes of recurring layout deviations in design system components. The cause was the integration of visual regression tests (BackstopJS) into the build and approval process: deviations were not blocked, and reference images were replaced without approval.
Recommendations for a controlled workflow with mandatory approval and test results as a prerequisite for merging. Contributed to the successor system based on Lit/Web Components.
Technologies: Lit, Web Components, SCSS, Gulp, BackstopJS, GitHub Enterprise, JFrog Artifactory
Senior Frontend Developer
HDI Deutschland AG
Design System & AI Integration
Design-to-code consistency of the enterprise design system made up of Lit-based Web Components following Atomic Design and fully compliant with WCAG. Compared Figma specifications with the SCSS implementation, converted deviations into development tickets, and established documentation standards for the internationally distributed team.
Evaluated, selected, and introduced Claude Code and GitHub Copilot in compliance with governance, compliance, and security requirements. Own AI toolkit: three Claude Code plugins with 31 agents and 11 Commands for shared context, PR reviews with quality gates, and component development, connected via MCP to the Figma API and Azure DevOps. Accessibility agent with eleven deterministic test cases found 14 accessibility errors; supplemented by axe-core tests with Playwright and visual regression tests.
Technologies: Lit, Web Components, TypeScript, Angular, Nx, Vite, Storybook, Playwright, axe-core, Style Dictionary, Design Tokens, SCSS, Figma, WCAG, Claude Code, GitHub Copilot, MCP, Azure DevOps, GitLab, Jira, Confluence, Scrum
UX/UI & Frontend Developer
HZD - Hessische Zentrale für Datenverarbeitung
Business application and design system
Three years of product development on FisBox, the central business application for case workers in Hessian state authorities. Accessible web interface with Telerik UI for Blazor and Kendo UI, web forms based on business requirements, in close coordination with the specialist departments; intensive work with Azure DevOps.
Follow-up assignment: Modernization of the WPF desktop application, learning XAML with AI support. The result is a complete design system with all controls, custom views, a searchable SVG icon explorer, and documented user journeys. WCAG 2.1 AA and BITV 2.0 throughout: contrast, keyboard operation, screen readers.
Technologies: C#, Blazor, Razor, Telerik, Kendo UI, WPF, XAML, HTML, CSS, SCSS, TypeScript, Angular, WCAG 2.1 AA, BITV 2.0, Azure DevOps, GitLab, Jira, Confluence, Claude Code, GitHub Copilot, Scrum
Frontend Developer
Bertelsmann for Lufthansa
Responsive newsletter templates
Developed and maintained responsive newsletter templates for Lufthansa, implemented in RPL, a template language derived from FreeMarker; extensive template logic in FreeMarker syntax.
Technologies: RPL, FreeMarker, HTML email, CSS, Responsive Design
Frontend Developer
queo for the DAAD
Relaunch of research-in-germany.org
Replaced a Magnolia instance that had grown over many years with a newly established system in a short time; complete frontend setup with FreeMarker templating, asset pipeline, I18n, design system, and accessible forms according to WCAG, implemented based on Figma templates; tests with Playwright.
Technologies: JavaScript, React, HTML, SCSS, Bootstrap 5, Magnolia, FreeMarker, Java, Playwright, Figma, WCAG, I18n, REST, GraphQL
Frontend Developer
diconium for Carl Zeiss AG
B2B Metrology Shop
Further development of the Intershop-based B2B shop shop.metrology.zeiss.de in a team distributed across several continents, with English as the project language; code quality, multilingual support, accessible interface.
Technologies: TypeScript, React, HTML, SCSS, Bootstrap 5, Intershop, ISML, Java, I18n, WCAG, REST, GraphQL
Lead Frontend Developer
Neofonie for Bechtle AG
bechtle.com
Frontend lead for Magnolia (FreeMarker) and SAP Hybris Commerce, coaching the team and establishing best practices; ensured performance during the B2B demand surge during the coronavirus pandemic; documented components in Storybook.
Technologies: JavaScript, React, jQuery, HTML, SCSS, Tailwind CSS, Storybook, Magnolia, SAP Hybris Commerce, FreeMarker, Java, Gulp, REST, GraphQL
Frontend Developer
BASF Business Services GmbH
Performance emergency response for basf.com
Accelerated basf.com in Adobe Experience Manager by 1440 % within six months; cleaned up and restructured the codebase; set up automated tests with Jest, Selenium and Cucumber; trained the team in scalable CSS architecture.
Technologies: TypeScript, JavaScript, HTML, SCSS, Tailwind CSS, AEM, HTL, Jest, Selenium, Cucumber, Webpack
Frontend Developer
mobilcom-debitel GmbH
SAP Hybris Commerce
CMS components (SmartEdit) for the SAP Hybris Commerce shops of all brands (B2C, B2B, Saturn, Media Markt); maintenance, refactoring and modernization of legacy code; mentoring and training in CSS architecture.
Technologies: HTML, SCSS, Foundation 6, ITCSS/BEM, TypeScript, jQuery, Angular, Gulp, SAP Hybris Commerce, JSP/JSTL, SmartEdit
Frontend Developer
DEICHMANN SE
SAP Hybris Commerce
Optimized the usability, performance and CSS architecture of the online shop during the migration to Hybris 6; refactoring; introduced visual regression testing with BackstopJS.
Technologies: HTML, SCSS, Foundation 6, BEM, JavaScript, Handlebars, jQuery, Angular, Gulp, BackstopJS, SAP Hybris Commerce, JSP/JSTL
Frontend Developer
Kühne + Nagel
Design System for Booking Flows
International booking flows for Air, Sea and Overland converted to a responsive component system: Design System, Pattern Library and Web Components; WCAG; visual regression testing with BackstopJS; team mentoring.
Technologies: HTML, SCSS, Bootstrap 4, ITCSS/BEM, JavaScript, React, Nunjucks, Web Components, BackstopJS
Frontend Consultant
Rossmann
SAP Hybris Commerce
Trained and supported the in-house team in SAP Hybris Commerce (Storefront, JSP/JSTL), Magnolia integration and CSS architecture; Programming by Example, mentoring, supervising.
Technologies: HTML, SCSS, Bootstrap 4, ITCSS/BEM, JavaScript, jQuery, Magnolia, SAP Hybris Commerce, JSP/JSTL
Frontend Consultant
diconium for Robert Bosch GmbH
IoT Marketplace
Advised and trained an international team in building the IoT Marketplace on SAP Hybris Commerce and technically stabilized the project; Design System and web forms.
Technologies: HTML, SCSS, JavaScript, jQuery, Gulp, BrowserSync, I18n, SAP Hybris Commerce, JSP/JSTL
Interim Head of Frontend Development
hmmh multimediahaus AG for bonprix (Otto Group)
Frontend architecture, planning and team building for the complete rebuild of the online shop; first fully responsive prototype, Pattern Library, Design System, frontend curriculum and workshops. Framework-free, long-lasting concept, gradually implemented by the existing team; launched in 2025 on this basis.
Technologies: JavaScript (framework-free), HTML, SCSS, ITCSS, Handlebars, Gulp, BrowserSync, BackstopJS, SAP Hybris Commerce
Frontend Developer
hmmh multimediahaus AG for hessnatur
Mobile-first Migration
Migrated an inherited shop project to Foundation 6 using a mobile-first approach; Hybris JSP tags, Gulp/BrowserSync pipeline; introduced visual regression testing with BackstopJS.
Technologies: HTML, SCSS, Foundation 6, ITCSS, JavaScript, jQuery, Gulp, BrowserSync, BackstopJS, SAP Hybris Commerce, JSP/JSTL
Frontend Developer
CAMPOINT AG
Templating System and Style Guide
Templating system based on KISS, DRY and Convention over Configuration with ITCSS, BEM and Atomic Design; style guide for the product relaunch; training for the backend team; galleries and performance.
Technologies: HTML, LESS, Bootstrap, JavaScript, React, Smarty
Interim Frontend Manager
Franke und Bornberg Research GmbH
Built the frontend department; modernized comparison products with complex, accessible forms (Form.io); pattern library and performance.
Technologies: HTML, LESS, Bootstrap, JavaScript, Form.io, Smarty
Frontend Developer
Cisco Systems GmbH
Cisco Asset Management Suite
Redesigned the GUI of the Cisco Asset Management Suite (Qooxdoo); redesigned the product help together with the support team in India (RoboHelp).
Technologies: HTML, SCSS, Bootstrap, JavaScript, Qooxdoo, RoboHelp, Photoshop
Interim Frontend Manager
REWE Group (DER Touristik)
der.com
Analyzed and realigned the Magnolia/FreeMarker system after a failed relaunch; defined frontend structures and methods, consolidated agency teams; migration from Magnolia 4.5 to 5; Kanban and Scrum.
Technologies: Magnolia, FreeMarker, HAML, HTML, SCSS, BEM, JavaScript, jQuery, Angular, Knockout.js, Jira, Confluence, Kanban, Scrum
Lead Frontend Developer
Deutsche Telekom AG
Relaunch videoload.de
Led the frontend relaunch of videoload.de. Analyzed the expensive CoreMedia legacy system and replaced it with a lean system that could be maintained by two people: FreeMarker templating with an HAML-for-FreeMarker parser developed by the team.
Technologies: CoreMedia (replacement), FreeMarker, HAML, HTML, SCSS, BEM, JavaScript, jQuery, Jira, Confluence, Scrum, Kanban
Senior Frontend Developer
Dievision Agentur für Kommunikation
Corporate and brand websites, mainly on Magnolia CMS: TUI AG (corporate website, three relaunches), Viacom (MTV, VIVA, Nickelodeon, Comedy Central), Mercedes-Benz Bank, Shure, Börsen AG, Evangelische Landeskirche Hannovers, Niedersächsische Sparkassenstiftung, BIG direkt gesund.
Technologies: HTML, CSS, SASS, HAML, JavaScript, jQuery, JSP/JSTL, FreeMarker, XML, XSLT, Ruby on Rails, Magnolia CMS
Industry experience
See where this freelancer has spent most of their professional time.
Experienced in Advertising, Information Technology, Tourism, Government and Administration, Retail, and Telecommunication.
Business area experience
See which departments and functions this freelancer has contributed to most.
Experienced in Information Technology and Product Development.
Summary
Senior Frontend Developer and UX Engineer with over 25 years of experience in corporations, public authorities, and agencies. Focused on maintaining and developing UI libraries and design systems in close collaboration with UX/UI designers: components with Web Components (Lit), Design Tokens, Storybook, and Figma alignment, most recently in insurance and financial services. Translates UX and design requirements into high-performance, accessible frontend solutions and ensures a consistent user experience across multiple applications. Many years of experience with Server-Side Rendering using Java template engines: over ten years of FreeMarker (telecommunications, tourism, IT services, numerous Magnolia projects) as well as JSP/JSTL in SAP Hybris Commerce. Hands-on and operational in day-to-day business; accessibility according to WCAG 2.1 AA is standard.
- AI Toolkit for an Enterprise Design System (HDI): Three Claude Code plugins with 31 specialized agents for review, component development, and accessibility, connected to Figma and Azure DevOps; an accessibility agent with eleven deterministic test cases found 14 errors.
- Long-lasting architecture (bonprix): The framework-free frontend concept developed in 2017 is still in use today; in 2025, the new bonprix website went live on this basis.
- Performance in an emergency assignment (BASF): Accelerated basf.com by 1440 % within six months, measured before and after with browser performance tools and the client’s monitoring system.
- From web to desktop assignment (HZD): The accessible web interface for the state administration directly led to the follow-up assignment to modernize the desktop application together with the complete design system.
Skills
- Ui Libraries & Design Systems: Component Libraries With Lit/Web Components, Atomic Design, Design Tokens (Style Dictionary), Storybook, Figma, Pattern Libraries; Visual Regression Testing (Backstopjs)
- Server-Side Rendering: Java Template Engines: Freemarker (Over Ten Years), Jsp/Jstl (Sap Hybris Commerce), Rpl; Magnolia Cms, Adobe Experience Manager (Htl)
- Ux Understanding: Collaboration With Ux/Ui Design, Interaction And Navigation Concepts, User Journeys, Consistent Ux Across Multiple Applications
- Frontend: Html, Css, Scss (Sass), Javascript, Typescript, Web Components, Lit, React, Node.Js, Rest, Graphql
- Accessibility: Wcag 2.1/2.2 Aa, Bitv 2.0, En 301 549; Screen Readers, Keyboard Operation, Contrast, Focus, Accessible Forms And Components
- Quality & Tooling: Playwright, Axe-Core, Backstopjs, Jest, Vite, Webpack, Gulp, Git, Gitlab, Github, Azure Devops, Jira, Confluence, Scrum, Kanban; Ai-Assisted Development With Claude Code
Languages
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Experience
Global experience
Expertise
Profile
Frequently asked questions
Have questions? Find more information here.
Jens is based in Hanover, Germany.
Jens speaks the following languages: German (Native), English (Advanced).
Jens has at least 27 years of experience. During this time, Jens has worked in at least 7 different roles and for 21 different companies. The average length of individual experience is 1 year and 3 months. Note that Jens may not have shared all experience and actually has more experience.
Based on recent experience, Jens would be well-suited for roles such as: Frontend Developer, Senior Frontend Developer, UX/UI & Frontend Developer.
Jens's most recent position is Frontend Developer at Volkswagen Financial Services AG.
In recent years, Jens has worked for Volkswagen Financial Services AG, HDI Deutschland AG, HZD - Hessische Zentrale für Datenverarbeitung, Bertelsmann for Lufthansa, and queo for the DAAD.
Jens is most experienced in industries like Advertising, Information Technology, and Tourism. Jens also has some experience in Government and Administration, Retail, and Telecommunication.
Jens is most experienced in business areas like Information Technology, Product Development, and Quality Assurance.
Jens has recently worked in industries like Tourism, Information Technology, and Government and Administration.
Jens has recently worked in business areas like Information Technology, Product Development, and Quality Assurance.
Jens will be available full-time from November 2026.
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The median daily rate is the middle value of all daily rates — half of comparable freelancers charge less, half charge more. Unlike the average, it is barely affected by outliers.
Calculated based on our freelancers’ daily rates as of 17 Oct 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
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