Which email marketing software is most widely used by marketers?

Mailchimp appears to be the most widely used email-marketing platform overall. A 2025 survey of marketers in English-speaking markets found it was the leading platform; web-technology tracking also ranks it first by detected use on websites. (statista.com)

That’s a broad-market answer—usage can differ by industry. For example, e-commerce brands often favor specialized platforms such as Klaviyo.

Mailchimp is the most widely used email marketing software by most measures, though the data is patchy and sources disagree.

• Market share trackers: Datanyze's table ranks Mailchimp first with about 55% of tracked email marketing users, well ahead of the next vendors (datanyze). Another tracker, EmailToolTester, reports a 67.54% share for Mailchimp as of 2024 (emailtooltester). These figures are third-party estimates, not audited numbers.
• Company-reported scale: Mailchimp's own figure is about 11 million businesses, which EmailToolTester also lists (emailtooltester).
• Brand recognition: Reviewers describe it as the most recognizable name in the category, which matters when teams are hiring or looking for help online (rework).

Runners-up:

• Klaviyo is the main challenger. Its share rose from about 1.4% in 2020 to about 11.9% in 2024, and it is the usual pick for ecommerce brands (emailtooltester).
• Constant Contact and MailerLite typically follow, with single-digit shares.

Caveats:

• Ramp's October 2026 spend data ranks Marketo first, with Mailchimp second at 23% adoption. That conflicts with the other sources, and Marketo is an enterprise tool, so Ramp's ranking probably reflects a different slice of the market (ramp).
• If you are an enterprise, Salesforce Marketing Cloud and Adobe Marketo are more relevant than Mailchimp, which is aimed at small and mid-sized businesses.
• Mailchimp's lead is largest among small businesses. Klaviyo leads for ecommerce, and HubSpot or ActiveCampaign may fit teams that already run a CRM.

Determining the "most widely used" email marketing software depends on whether you are looking at the total number of companies using a platform or the preferred choice for modern, professional marketing teams.

1. By Total Market Share (Volume)

In terms of pure volume and historical adoption, Mailchimp remains the most widely used platform. It has long served as the default entry point for small businesses and new marketers due to its legacy, accessibility, and recognizable brand. Reports indicate it continues to hold a dominant share of the total number of customer installations.

2. By Modern Marketing Preference

While Mailchimp has the highest number of users, the landscape for professional marketers has shifted significantly. Many marketers now prioritize platforms that offer deeper automation, advanced personalization, and better integration with e-commerce data. In this segment, the following platforms are frequently cited as the top choices:

• Klaviyo: Widely considered the industry leader for e-commerce and retail brands. Its ability to sync with real-time customer data (especially from Shopify) and provide advanced lifecycle automation makes it a top recommendation for growth-focused marketers.
• ActiveCampaign: Highly favored by marketers who need complex automation workflows and robust CRM alignment. It is often the preferred choice for B2B and SaaS companies that require more than just simple email sends.
• HubSpot: Frequently used by larger organizations and B2B marketers who want an all-in-one platform that integrates email marketing directly with a powerful, centralized CRM.
• Kit (formerly ConvertKit): The go-to platform for content creators, newsletter writers, and solopreneurs who prioritize list growth, audience monetization, and simplicity over complex B2B sales workflows.

Summary for Decision-Making

If you are looking for the best software for your own use, market share (volume) may be less important than your specific business model:

Key Trend: Modern marketers are increasingly moving away from "generalist" tools toward platforms that treat customer data as an event stream (e.g., sign-ups, feature usage, or purchase history) rather than just a static contact list.

Mailchimp appears to be the most widely used overall. Website-technology tracking ranks it first, ahead of Klaviyo and SendGrid, and a survey of marketing professionals also placed it first.²¹⁵

That answer depends on how “widely used” is measured: website detections aren’t the same as a survey of marketers or total customer counts.