Maximilian Rast

Maximilian Rast

Co-Founder and CEO @ Klar

More than a decade in European eCommerce. Previously led marketing as a CMO at yfood and ottonova.

About

Maximilian Rast co-founded Klar in 2021 together with Cillié Burger and Frank Birzle.

The product came out of a problem he had himself. Running marketing as a CMO at yfood, he could not find a suitable tool that covered his reporting & attribution needs, putting acquisition spend, contribution margin and retention into the same report. So the three of them built one themselves. Klar launched publicly in March 2022, backed by a €2.3 million seed round led by Cherry Ventures with angels from yfood, SellerX, Xentral, Juni, Alaiko, Moss and OMR.

Today Klar is used by more than 2,000 eCommerce brands, among them BLACKROLL, Deutsche See, HOLY and Loop Earplugs. Max also runs eCom Unity, Klar's community of more than 2,500 European eCommerce operators. He writes and speaks about the part of the job he spends most of his time on: telling marketing spend that works from marketing spend that only looks like it does.

What he works on

Rast writes about measurement from the operator's side of the table, not the vendor's.

He has spent years on the spending side. At yfood he scaled marketing during the brand's fastest growth phase; the marketing team went from 15 to 45 people in six months, revenue from 20 to 100 million, and the brand entered eight new markets in 18 months. At ottonova, he ran marketing for a digital insurer, a category where a single misread channel report is expensive. His first years in eCommerce were spent in Rocket Internet's venture Zando (African version of Zalando), where nothing could be assumed, and everything had to be measured.

He sees the numbers of a large part of the German-speaking market. Klar connects shop systems, ad platforms, email tools and analytics for more than 2,000 brands. What he writes from are the patterns across those accounts, not one brand's anecdote.

He is in the room with the operators. eCom Unity brings together more than 2,500 European eCommerce founders and senior operators, online and at its community events in Berlin, Munich, Hamburg and Cologne. Questions asked there tend to show up in his writing a few weeks later.

Topics

Marketing attribution and unified measurement · Contribution margin and eCommerce P&L · Customer lifetime value, cohorts and retention · Paid media efficiency (MER, ROAS, CAC) · Incrementality testing and marketing mix modelling · eCommerce data infrastructure and tracking

Selected appearances

  • Meta Agency Summit 2026 — "The State of Marketing Measurement - From Conflicting Truths to Unified Attribution."
  • Ads Camp 2026 — "The State of German eCommerce - and the art (& science) of not wasting your money."
  • TikTok For You Summit 2025 — “Attribution without the Black Box - How to create alignment in your team, move faster and profitably scale your eCommerce business.”
  • E-Commerce Decoded #24 — "Über KLAR, Rocket Internet, die Samwers und den deutschen E-Commerce", September 2023
  • New Com Podcast #38 — "Ruf deine Kunden an, um sie zu verstehen!"
  • Ecommerce Coffee Break #97 — "Experiences From Growing Ecommerce Businesses In Emerging Markets"
  • Digital Commerce Talk #5 — "Warum Daten im E-Commerce falsch verstanden werden"
  • AdsCamp — speaker, on scaling brands to seven- and eight-figure ad budgets profitably
  • eCom Unity Unplugged — Klar's operator event series, Vol. 1 to Vol. 6, Berlin
  • OMR 2024 @ Yellow Stage — “Wie die besten E-Com Brands ihre Retention Rate optimieren” (Link)
  • K5 2024 — “Retention beginnt vor der ersten Email. Wie Deutschland’s schnellstwachsende Beauty Marke 47% ihrer Neukunden in loyale Wiederkäufer verwandelt.”

More appearances as a speaker

JTL Connect 2024, NewCom Summit 2024, TikTok For You Summit 2024, TikTok Webinars, Ads Camp 2025, Merchant Inspiration Talks 2024, ECommerce Agency Summit 2024, 2025 & 2026, THIS IS MARKETING 2024

Elsewhere

How this content is produced

Max is the Founder of Klar and sells one of the tools covered in some of our articles. Where that is the case, the article says so at the top, states the criteria before the result, and links the vendor documentation behind every claim so readers can check it themselves. Facts are verified against primary sources, vendor documentation, pricing pages, security portals, on a stated date, and corrections are made in the article with the date changed.

Contact

For press enquiries, data requests or a second opinion on your measurement setup:

info@getklar.com