Choosing between Klaviyo and Mailchimp is one of the most common decisions UK businesses face when they get serious about email marketing. Both are well-built platforms with substantial user bases, and most of the comparisons you’ll read online dance around the actual question, which is: which one fits your business?

The honest answer isn’t “the best one”. Klaviyo and Mailchimp were built for different jobs, and the right pick depends almost entirely on what kind of business you’re sending email from. We’ve worked with both platforms across client projects, and we’ve seen the costs of getting this decision wrong. Months of work moving from one to the other, lost segmentation, broken automations.

This is the post we wish existed when clients ask us. The structure: what each platform is genuinely built for, when each one wins, the real cost picture, what migration actually looks like, and a clear way to decide.

What each platform was actually built for

The most important thing to understand about both tools is the audience they were designed for.

Mailchimp started as a general-purpose email tool, built for businesses, agencies, and freelancers who wanted to send newsletters and basic campaigns to a list. It’s grown into a broader marketing platform over the last decade, and Intuit acquired it in 2021 for $12 billion. It’s still where most people first encounter email marketing software, and it remains genuinely good at the core newsletter use case.

was built from day one for ecommerce. Specifically, for Shopify stores who wanted email that could behave like a real marketing channel, with deep segmentation based on what customers had browsed and bought, automated flows triggered by purchase behaviour, and revenue tracking that connected email to actual sales. Klaviyo became the default ecommerce email platform in the late 2010s and has steadily extended its reach into SMS, reviews, and now broader customer data functionality.