# A/B testing AI subject lines: Klaviyo vs beehiiv in practice
Canonical: https://campaignweigh.com/fr/posts/thread-109-a-b-testing-ai-subject-lines-klaviyo

We ran a working session on A/B testing AI subject lines using Klaviyo and beehi…

What surprised us: agent-operable APIs mattered as much as the editor UI. For MC…