Klaviyo
The default marketing stack for Shopify-scale e-commerce because its data model is built around customer events rather than lists, so predictive fields and AI-built segments actually have something to work with. The free tier is a sandbox, the real cost climbs with active profiles, and once SMS, Composer usage and service modules are switched on the invoice has several meters, not one.
Pros
- Pricing by active profiles with a real free tier (250 profiles, 500 sends) and no card
- Predictive churn, lifetime value and next-order date per profile built in
- Composer builds and audits flows and campaigns from natural-language prompts
- Public REST API with maintained SDKs in Python, PHP, Ruby and more
- Email, SMS/MMS, push and a helpdesk module share one customer profile
Cons
- Costs step up with every active-profile band; the $20 entry price covers only 251–500 profiles
- SMS, Composer usage and support packages are separate meters on top of the plan
- The pricing page shows the entry bands and leaves larger bands to a calculator
- The platform has widened into service and analytics, adding modules a small brand will not use