Available for new projects

Leander
Gilles

I'm a software developer from Frankfurt am Main, Germany. Building high-performance web architectures with surgical precision.

Leander Gilles
Leander Gilles • 8+ years of experience

Portfolio

Selected Projects

Global Website Relaunch project preview

Global Website Relaunch

2025 - Present

Leading German Automotive Brand

Rebuilt a global website platform spanning over 80 markets, more than 50,000 pages, and 10M+ monthly visitors with Astro, Storyblok migration, frontend development with JavaScript/TypeScript, and a custom migration script.

  • Astro
  • TypeScript
  • HTML
  • CSS
  • Vite
  • React
  • Accessibility
  • Web Components
  • Storyblok
Picture next to the office at GuideCom in Münster

Design System Modernization

2025 - 2025

GuideCom AG

Modernized a design system for an HR suite, including migration from Polymer to Lit, frontend buildchain optimization, requirements analysis, component improvements, frontend development with JavaScript/TypeScript, accessibility implementation, and software testing.

  • Lit
  • Polymer
  • TypeScript
  • HTML
  • CSS
  • Vite
  • React
  • Java
  • Storybook
  • GitLab
  • Figma
  • Accessibility
  • Web Components
Collider project preview

Collider

2024 - 2024

d.quarks GmbH

Collider is a tool that helps companies accelerate their digital transformation in a faster, more cost-efficient, and scalable way. It provides structured guidance, information, and expert access to help organizations build the capabilities needed in a digital world. Responsibilities included implementing the API with AWS Lambda, delivering new frontend features and bug fixes, and executing database migrations.

  • Angular 17
  • Angular Material
  • RxJS
  • SASS
  • AWS Lambda
  • SST
  • Node.js
  • Postgres
  • Cognito
  • TypeORM
  • Scrum
  • GitHub
  • Serverless
Die Techniker Haupteingang

Public Platform & Design System Rebuild

2024 - 2025

Die Techniker

Built a design system and redeveloped the public area of tk.de. Delivered new Web Components with Lit, new CMS modules with Freemarker templates, Scrum code reviews, performance analysis and optimization measures, React micro-frontends, and modernization of the frontend framework to Astro.

  • TypeScript
  • Lit
  • Java 17
  • Astro
  • Playwright
  • Node.js
  • Vite
  • React
  • Scrum
  • GitHub

Landing Pages & Forms Modernization

2022 - 2023

comdirect

Worked as a frontend developer on the comprehensive modernization of landing pages and forms on comdirect.de. Implemented extensive updates based on revised design specifications, with a strong focus on SEO and accessibility. Responsibilities included reworking and implementing forms and landing pages, updating the design system with Lit to ensure a consistent UI across the website, ensuring accessibility compliance and SEO best practices, and developing an Astro proof of concept.

  • Angular 17
  • Astro
  • RxJS
  • Less
  • Lit
  • Web Components
  • Jenkins
  • Node.js
  • Storyblok
  • Storybook
  • Design Systems
  • WCAG
Commerzbank Tower in Frankfurt a. M.

Public Website Redesign & CMS Integration

2021 - 2022

Commerzbank

Contributed to the comprehensive redesign of the public area of Commerzbank.de, with responsibility for frontend development and seamless CMS integration with the frontend. Responsibilities included implementing React components based on design specifications, improving development speed by introducing TypeScript modules, and developing and executing comprehensive unit tests and automated browser tests to ensure system quality and stability.

  • React 18
  • Next.js
  • Remix
  • Azure
  • Contentful
  • Azure Functions
  • Azure DevOps
  • Node.js
  • Storybook
  • GraphQL
  • Styled Components
  • Scrum
  • Design Systems
  • WCAG
  • Accessibility

Advisory Platform Modernization

2021 - 2021

German Retail Bank

Built a customer-facing web application for financial guidance and advisor support, including features such as chatbot assistance, video calls with customer support, and promotional offer displays. Led the frontend team, gathered requirements with stakeholders, implemented backend microservices, authored Terraform scripts, and configured Azure DevOps CI/CD pipelines.

  • React
  • TypeScript
  • Three.js
  • Spring Boot
  • Kubernetes
  • Azure
  • Azure DevOps
  • Terraform
  • OpenAPI
  • Redis
  • Tomcat
  • JUnit
  • Cloud-Native
  • DevOps
  • CI/CD

Travel Expense Card Platform Modernization

2019 - 2021

German Retail Bank

Modernized software used to manage travel expense cards. These virtual cards streamlined transparent business travel expense accounting and reduced the workload for finance teams. Designed and implemented the frontend architecture, built the UI for processing and analyzing customer data (including dozens of forms, tables, and charts), collaborated closely with the client on requirements gathering, implemented invoice generation, contributed to backend development, and optimized database queries.

  • Angular
  • Kotlin
  • Angular Material
  • TypeScript
  • Spring Boot
  • Apache FOP
  • JPA
  • Hibernate
  • RabbitMQ
  • Oracle
  • Docker
  • Tomcat
  • JUnit

Robo-Advisor Platform Evolution

2018 - 2019

Digital Wealth Management Platform

Contributed to a white-label robo-advisor product that recommends investment portfolios based on customer goals and risk tolerance, with hundreds of product variations and assets under management exceeding 4 billion euros in customer funds. Estimated, refined, and implemented user stories authored by business analysts, migrated a monolithic frontend toward a micro-frontend architecture, and implemented frontend features according to design requirements.

  • AngularJS
  • TypeScript
  • Jenkins
  • Java EE
  • Keycloak
  • JUnit
  • Scrum
  • Micro-frontends

Services

Architectural Services

Transforming complex requirements into seamless digital experiences through specialized engineering.

Headless CMS Integration

Decoupled content management for faster delivery, better security, and omni-channel flexibility.

  • Contentful & Sanity Specialist
  • Dynamic Content Modeling
  • Multi-language Support

Full-stack web development

End-to-end solutions using modern frameworks that prioritize scalability and future-proof codebases.

  • Custom SaaS Architectures
  • API Design & Integration
  • Real-time Data Systems

Website Performance

Optimizing Core Web Vitals to improve search rankings and user retention through lean engineering.

  • Performance audits
  • Priorizited optimization roadmap
  • Hands-on implementation

Contact

Let's Talk

Tell me a bit about your project and I will get back to you.

leander.gilles@58agents.com