Conversion optimisation
A/B tests, analytics and steady improvement. We find out what gets visitors to buy or get in touch, and build on it step by step.
Every change shows up in the numbers.
Design and UX studio · in Germany since 1999, near Zurich since 2026
Sebastian Herth, with Claudia Smolinski from our partner studio in Germany: UX, interface design, accessibility and copy for companies and agencies in Switzerland, Germany and Austria. In English or German.
Clients include
- EnBW
- Deutsche Telekom
- 1&1
- RTL Interactive
- Metro*
- Siemens*
* as agency partner
Services
From strategy to microcopy – the same two people.
UX audit
We go through your website or app screen by screen and show you where people get stuck.
You get the findings ranked by impact, each with a fix.
About the UX auditAccessibility (WCAG)
We audit by hand to WCAG 2.2 AA and design the fixes in your brand.
Since June 2025, the European Accessibility Act requires it for many online services.
About accessibilityBrand design and design systems
We develop your brand from strategy and identity to a system every team can work with.
It stays recognisable as it grows.
UX and interface design
Interfaces for websites and apps, from first sketch to clickable prototype.
Tested before anyone writes code.
UX writing
Claudia Smolinski writes the words in your interface and on your website, from error messages to the home page.
Your customers understand what to do the first time they read it.
Where to start
Start with fifteen minutes.
Send us a link. We’ll go through it with you on a free video call and tell you what we see – no slides, no sales pitch. If a full audit makes sense, scope and price are fixed before anything starts.
UX audit
Expert reviewFrom friction to flow.
We go through your key journeys the way your customers do – navigation, forms, checkout, copy – and rank every problem by what it costs you. Each finding comes with a fix.
- Key journeys, reviewed by hand
- Findings ranked by impact
- Fixes in design and copy
- Report and video walkthrough
Accessibility audit
WCAG 2.2 AAAccessibility starts here.
Since June 2025, the European Accessibility Act has covered many digital products sold in the EU. We test your pages by hand against WCAG 2.2 AA and turn every barrier into a fix your developers can ship.
- Manual testing to WCAG 2.2 AA
- Barriers ranked by urgency
- Fixes that fit your brand
- Report and video walkthrough
Scope and price are fixed before we start.
Clients
Clients who stay are the best reference.
A selection since 1999 – projects by atelier21 in Germany, with each client’s sector in case a name is new to you.
01 / 03
EnBW
Energy
UX and UI design, consulting, design system contribution, WCAG accessibility, website optimisation
02 / 03
1&1
Telecoms
UX design, prototyping, conversion optimisation, A/B testing
03 / 03
Deutsche Telekom
Telecoms
App and interface design, mobile style guide contribution
- EnBWEnergyUX and UI design, consulting, design system contribution, WCAG accessibility, website optimisation
- 1&1TelecomsUX design, prototyping, conversion optimisation, A/B testing
- Deutsche TelekomTelecomsApp and interface design, mobile style guide contribution
- SerafiniRetail interiorsDesign and consulting, catalogue
- MTVMediaMicrosite design
- RTL Interactive (Starbet)MediaUX and interface design, corporate design, mobile style guide
- Siemens*TechnologyInterface design
- BlancoKitchen productsUX/UI consulting, web design
- E.ON*EnergyWeb design
- Deutsche FamilienversicherungInsurancePrint design, campaign communication
- Metro*WholesaleUX design, prototyping, app design
- Galeries Lafayette*RetailOnline shop design
- Sat.1*MediaWeb design
- Volkswagen*AutomotiveCopywriting
- Netze BWEnergy networksUX and UI consulting
Delivered as agency partner.
About
Two crafts. One standard.
You talk to the people who do the work. Since 1999, atelier21 in Germany has worked for Deutsche Telekom, EnBW and the State of North Rhine-Westphalia. Since 2026, Sebastian Herth has had his own studio in Switzerland, near Zurich.
Sebastian Herth
Design · UX · design systems
Founded atelier21 in 1999. Read German literature and art history in Mainz, then studied communication design in Düsseldorf. Since 2010 he has worked inside large product teams, from Deutsche Telekom to EnBW, and he has taught UX and typography since 2008. A cool head with a soft spot for detail.
Claudia Smolinski
Copy · content · social
Designer, copywriter and art director; partner in atelier21 Germany since 2009. Claudia studied communication design in Düsseldorf and psychology in Bochum – advertising psychology in particular – with placements in London, Bologna and Milan. She sees the whole picture and stays calm when nobody else does.
“Aesthetics, function and form have to work as one.”
Contact
Fifteen minutes on video, free. Send a link beforehand and we’ll come prepared. We answer in English or German, on Central European Time.