Which email marketing tools connect with the most other apps?

ActiveCampaign appears to have the largest published integration count among the email-marketing platforms I checked: it advertises 1,000+ app integrations. (activecampaign.com)

| Mailchimp | 300+ | Broad general-purpose selection, including tools such as Shopify, Salesforce, Canva, and QuickBooks. (mailchimp.com) |

Bottom line: If you mean the biggest advertised catalog, start with ActiveCampaign. For an online store, compare Klaviyo and Omnisend based on whether they natively support your specific store and ecommerce apps—not just their total counts.

Counts aren’t perfectly apples-to-apples: vendors may count native integrations, marketplace apps, or third-party connectors differently. If you tell me which apps you need to connect, I can narrow this down to the best fit.

Based on the sources I found, HubSpot and Mailchimp have the largest native integration counts among email marketing tools, with HubSpot generally highest. Klaviyo leads for ecommerce connections. These numbers are mostly vendor or review-site claims, and sources disagree on exact counts.

Largest native ecosystems

• HubSpot: Estimates range from over 1,000 integrations in the HubSpot marketplace to 1,600+ apps, and one comparison lists 2,000+ native integrations. It is a CRM-based suite, so its email tools sit inside a broader platform.
• Mailchimp: Counts vary a lot by source. One review cites 800+ native integrations, another says over 500 integrations, and others report over 330 integrations or 250+. The 800+ figure looks like an outlier.

Strong ecommerce connections

• Klaviyo: The company's own comparison page lists 350+ pre-built integrations, and another source says it connects natively with platforms such as Shopify, BigCommerce, WooCommerce, Magento, and Salesforce Commerce Cloud. Its Shopify sync is often called its strongest connection. One source reports 450+ native integrations, but that figure is unverified.
• Omnisend and ActiveCampaign also have solid ecommerce and CRM links, though with fewer total integrations.

Smaller ecosystems

• AWeber lists 750+ third-party integrations, which is high, but most of its value is in design tools like Canva.
• MailerLite offers fewer third-party integrations than Mailchimp.

Workaround: Zapier
If you need a niche app, Zapier can link an email tool to thousands of others. One source says most email platforms only have native integrations with 5-10 popular tools, while Zapier connects to 7,000+. Zapier's own blog cites 9,000+ apps. Zapier links are usually slower to set up and can be less deep than native connectors.

Which to pick

• For the widest general app catalog, choose HubSpot (if you want a full CRM) or Mailchimp (if you want a simpler email tool).
• For an online store, Klaviyo usually offers the deepest data sync.
• Check whether the specific apps you use are native integrations or Zapier-only, because that affects how well they work.

When choosing an email marketing tool based on its ability to connect with other apps, Mailchimp and ActiveCampaign consistently stand out as the top choices due to their extensive native integration libraries and deep support for automation platforms like Zapier and Make.

Why These Tools Lead in Integrations

Most modern email marketing platforms support third-party connections, but they differ in "depth"—the number of triggers, actions, and data points they can share with other apps.

• Mailchimp: As one of the most widely used platforms, it boasts a massive ecosystem. It is often the first tool supported by new SaaS applications, and its Zapier integration is exceptionally deep, offering hundreds of pre-built workflow templates that make connecting it to e-commerce, CRM, and social media tools straightforward.
• ActiveCampaign: Often cited as the best choice for businesses needing complex, "no-code" automation. Its integrations are designed to handle more than just simple data syncing; they allow for advanced workflows where CRM objects, deal updates, and behavioral tags trigger actions across your entire tech stack.
• HubSpot: While it is a full CRM platform rather than just an email tool, its "app marketplace" is one of the largest in the industry. If your goal is to have your email marketing perfectly synced with sales, service, and marketing data, HubSpot’s native integration capabilities are unmatched.

How to Evaluate "Connectivity"

When you are looking for the best fit for your business, consider these three levels of connectivity:

1. Native Integrations: Check if the email tool has a direct "plug-and-play" connector for the apps you use most (e.g., Shopify for e-commerce, Salesforce or Pipedrive for CRM, or WordPress for your website). Native integrations are usually faster, more reliable, and free of extra subscription costs.
2. Zapier/Make Support: Almost all major tools (Brevo, MailerLite, Klaviyo, etc.) support Zapier. However, the quality varies. Look for tools that offer more than just "New Subscriber" triggers; you want tools that support search actions, multi-step Zaps, and custom field mapping.
3. API Access: If you have technical resources or a unique tech stack, look for platforms with well-documented APIs. This allows you to build custom, bespoke integrations that aren't possible with standard connectors.

Summary Recommendation

• For maximum compatibility and ease of use: Mailchimp is the safest bet because almost every third-party app will have a native integration for it.
• For powerful, complex automation workflows: ActiveCampaign is the industry standard for connecting your email tool to deep CRM and sales data.
• For all-in-one CRM and Marketing: If you are willing to move your entire stack, HubSpot provides the most unified integration experience.

Mailchimp appears to have the broadest clearly documented native integration catalog among the tools in the sources I found: it advertises 300+ integrations, and Zapier’s comparison lists 330+ for Mailchimp versus 175+ for MailerLite. ¹²

Other sizable ecosystems include Brevo, which says it connects with 150+ tools, and HubSpot, whose app marketplace offers a large catalog—though the marketplace count isn’t limited to email-specific integrations. ³⁴

Bottom line: If you mean ready-made integrations built or listed directly by the vendor, Mailchimp is a strong bet. If you count automation connectors such as Zapier, several platforms can reach thousands of apps, so the practical difference depends on whether the specific connections you need work reliably and support the data flows you want. ²⁵

Counts are vendor- or directory-reported and may use different definitions, so they’re not perfectly apples-to-apples.