Klaviyo

If you sell physical products online, Klaviyo is the correct answer and the rest of this category is a compromise. That is an unusually strong claim for us to make, and it rests on one architectural fact: Klaviyo stores order and browse data as first-class customer attributes, so a segment like "bought twice, not in 90 days, spent over $200" is a two-minute build rather than a data project.

The consequences show up everywhere. Abandoned-cart, browse-abandonment, post-purchase and win-back flows are pre-built and actually good. Revenue attribution per flow and per campaign is native, which changes the conversation with a finance team from "email engagement improved" to "this flow earned $41,000 last quarter". The Shopify integration is the deepest of any platform here, and SMS shares the same profiles rather than living in a bolt-on.

The cost is real and worth stating plainly. Pricing scales with active profiles and gets expensive quickly — a 25,000-contact list runs several hundred dollars a month, materially more than Brevo or Mailchimp at the same size. The interface rewards competence rather than offering it; a marketer who has only used Mailchimp will need a week. And for B2B or service businesses without a product catalog, most of what you are paying for simply does not apply.

Our guidance: any ecommerce brand past roughly $20k monthly revenue should be on Klaviyo, and the attribution reporting usually justifies the premium within a quarter. Everyone else should look at ActiveCampaign or Brevo first.