Web Development
Custom websites and web applications for businesses that want a website that works just like they do: structured, fast, and scalable.
Web Development
Every website we build is developed specifically for each project. No themes, no templates, no page builders. We write the code ourselves because that allows us to maintain full control over performance, maintainability, and scalability.
Custom code
instead of templates
Modular design,
expandable at any time
Measurable Performance
From Day One
Why Custom Web Development Makes a Difference
Pre-made themes and page builders save time at the beginning, but cost more in the long run—in terms of performance, maintenance, and flexibility. We develop every website from the ground up. That means clean code without unnecessary dependencies, clear structures for your editorial team, and a system that grows with your needs. No workarounds that break with the next update. And no reliance on a theme provider who might stop updating tomorrow.
The Right CMS for Your Project
Depending on your needs, we use WordPress, TYPO3, or HubSpot CMS. WordPress is suitable for most corporate websites and offers a backend that editorial teams can quickly get the hang of. TYPO3 is used when multilingual support, complex permission structures, or enterprise-level requirements are needed. HubSpot CMS connects your website directly to CRM and marketing automation. If you’d rather work without a traditional backend, Webflow is another option. We’ll work with you to honestly determine which system is right for your project—even if the answer is sometimes “none of the above.”
We don't build websites using templates. Everything we create is developed individually for each project. Here's what we prioritize most in the process.
These companies know how we work
We write HTML, CSS, and JavaScript by hand. No page builders, no visual editors that generate bloated code. Instead: semantic markup that search engines and screen readers alike can understand. For our styling architecture, we rely on Tailwind CSS, which allows us to implement consistent designs efficiently without accumulating legacy CSS. We develop animations and interactions using GSAP or native JavaScript, depending on the requirements and complexity. Every page is tested on all relevant devices and browsers before it goes live. We check not only the presentation but also load times, interactivity, and visual stability based on the Core Web Vitals. The result: websites that load quickly, work on every screen, and remain stable even as content grows. This is the part that a web development agency should not outsource.
„The team at seitenweise consists of our graphic design and web development professionals. Whenever we need help, they’re always there for us—quickly and reliably. Thank you for the great collaboration!“
Sandra Meder
Sage
„seitenweise impressed us with fast delivery, friendly communication, and their patience in incorporating our requests! If you want a fast, attractive, and SEO-optimized WordPress website, you should have one built here.“
Michael Bykovski
Computerra
„Working with an agency requires good ideas, cutting-edge technology, and clear budgets with no surprises. But the personal chemistry has to be right, too. With seitenweise, everything was just right. It was really fun.“
Mathias Schwaben
Intervideo
„Since we started working with seitenweise, our website has improved significantly. In 2023, they used their extensive expertise to transform our static website into a dynamic WordPress site.“
Dirk Bockelmann
DFT
From the first meeting to go-live
Understanding Requirements
Together, we’ll clarify what your website or web application is intended to achieve: target audiences, features, content, integrations, and technical requirements. This will result in a concept that includes a site structure, a CMS recommendation, and a technical framework. During this phase, we’ll also define what your team should be able to maintain on its own later on and where fixed structures make more sense. This way, both sides know from the start exactly what the project entails.
Design and Prototype
We develop the visual design based on the concept. You’ll see drafts for the most important page types, provide feedback, and we’ll iterate until we reach the final result. From the very beginning, we consider how the design will be implemented in the CMS. Which elements can your team create, and where are fixed layouts the better choice? This saves time during development.
Development and CMS Setup
We implement the design as clean code and set up the CMS so that your editorial team can work independently. This includes custom content elements, page templates, and a clear backend structure with validations and help texts. If needed, we develop custom features or integrate third-party systems via APIs. Every component is designed with maintainability and scalability in mind.
Testing and Launch
Before the site goes live, we test its features, performance, responsiveness, and accessibility on all common devices and browsers. Your team will receive an introduction to the backend and will be able to enter initial content on their own. Once everything is set up and you give the green light, the site will go live. After that, we’ll remain available for enhancements, new requirements, or ongoing maintenance.
Frequently
Asked
Questions
Well-thought-out
Fast
We turn design into technology that works.
seitenweise is a digital agency based in Bielefeld, founded in 1999. With over 100 clients and more than 500 projects, we’ve proven that we build long-term partnerships, not just take on individual projects. Our focus is on custom web development using WordPress, TYPO3, and HubSpot CMS. Every website is built from the ground up—no themes, no templates, and no page builders. Many of our clients are from East Westphalia-Lippe, and many come from much farther away. We also offer strategy, UX/UI design, SEO, and video—all from a single source. Short communication channels, honest advice, and a team that knows your project—not just a ticket number.
Marcel and André are your points of contact at seitenweise. They're happy to answer any questions you may have about web development.
Whether it's a new website, a relaunch, or a technical enhancement: tell us where you're at and what you're planning. No strings attached—it'll take just 30 minutes.