AI subject-line tester/optimizer

Mailchimp (A/B testing)

Best for: Small teams already on Mailchimp wanting more variants (3) than Klaviyo's 2

Test up to 3 subject line/content/layout variations (paid plans only) with multivariate campaign reporting
Starting priceFree / Essentials $13/mo for A/B testing
Free tierFree plan exists but A/B testing requires Essentials ($13/mo)
RegionWest