Sebastian Käufer
OPEN FOR NEW PROJECTS Book a call

Senior Shopify developer & CRO partner

Shopify changes you can measure.

For brands and agencies. I find where a store loses orders, fix the measurement that hides it, and ship the change myself, in the theme.

Book a 20-min call For agencies →
Sebastian Käufer at his desk
You talk to the person who builds itYucatán · UTC−6

EV-01 · Live record · Nicebeam

The buy button sat below the fold. So I moved it.

On the top-traffic product page the add-to-cart sat below the iPhone fold, and the most-tapped element was the close button of a popup. Buy block moved up into one row, popup moved to 40% scroll, then 28 days measured against the 28 days before.

Read the full record →
Mobile add-to-cart 1.95% Before · 27 May – 23 Jun 2026 Buy block below the fold

More records

EV-02 · Migration5 langsWordPress and Vue moved to Shopify, then ongoing work, Zimply Natural EV-03 · Architecture523/523Theme files shared by two brands on two continents EV-04 · Audit12Findings, 5 critical, each with a dated capture, Puflow EV-07 · B2B0 appsPrices behind a passwordless login, Studio.tools

For brands

Your store, diagnosed and fixed.

CRO audit and implementation, tracking and consent, product and landing pages, custom themes, B2B and migrations.

See the work →

For agencies

A senior developer under your brand.

NDA by default, no client contact, your tools and Git. Fixed price per scope, pilot tickets from USD 450.

Partner details →

Selected work

MOBILE ADD-TO-CART · 28 DAYS+161%0%1%2%3%4%5%6%1.95%5.08%
Plate 01 · Measured CROEV-01
Nicebeam: mobile add-to-cart from 1.95% to 5.08% in 28 days
Zimply Natural product page
Plate 02 · MigrationEV-02
Zimply Natural: WordPress and Vue.js moved to Shopify in five languages
AU STOREEU STOREONE THEME523 / 523 FILES SHARED
Plate 03 · ArchitectureEV-03
Lighting manufacturer: two brands, one codebase
Finding 01 of the Puflow audit: the mobile cart drawer
Plate 04 · AuditEV-04
Puflow: 12 findings, each with a dated capture
01REGISTER02PRICES03COURSE04CERTIFY05REORDER06REFRESH
Plate 05 · B2B logicEV-05
Testing lab: train first, then buy, certificate included
METAGOOGLE ADSAFFILIATECONSENTEU OPT-INUS OPT-OUT
Plate 06 · ConsentEV-06
US costume brand: ad pixels now wait for consent
Studio.tools storefront
Plate 07 · Custom themeEV-07
Studio.tools: a custom B2B theme on Horizon

Next step

Something here close to your project?

Send the store URL and what isn’t working. I reply myself, in English, German or Spanish.

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About

Ten years in Munich agencies, six on Shopify.

I completed a three-year German dual apprenticeship as a certified software developer (Fachinformatiker Anwendungsentwicklung) in Munich, then spent about ten years building frontends in agencies, including ADAC.de. For the last six years I have worked on Shopify full time, now from Yucatán, Mexico, with the full US working day and EU afternoons in reach.

Completed projects
800+
Verified reviews
580+
Languages
English, German, Spanish
Working hours
Full US day, EU afternoon