Customer.io vs Klaviyo
Behavioral lifecycle automation for SaaS versus event-rich ecommerce automation.
What matters for early-stage startups
At an early stage the deciding factors are what the free tier actually covers, what the first paid invoice looks like, and how much of a founding engineer's week the setup costs. Feature depth that only matters at a million sends a month is noise until it is not.
| Priority | Customer.io | Klaviyo |
|---|---|---|
| Free tier | No permanent free tier; trial only | 500 emails to 250 contacts |
| Best published rate per 1,000 | Tiers not published in comparable form | Tiers not published in comparable form |
| Starts at | $100/mo (Essentials) | $45/mo for 5,000 emails |
| DX score | 7/10 | 6/10 |
| Deliverability | Good; reputation managed at the workspace level with optional dedicated IPs. | Solid for ecommerce traffic. |
| Operating since | 2012 | 2012 |
| Scheduling | Yes | Yes |
| SDKs | node, python, go, ruby, php, java | node, python, php, ruby |
| Webhooks | Yes | Yes |
For a pre-revenue or early-revenue team running a waitlist, a launch announcement, onboarding email, and the first transactional sends, Customer.io takes every priority that separates them here (developer experience and SDK breadth), while Klaviyo matches it on the rest. On free tier, Customer.io offers No permanent free tier; trial only against 500 emails to 250 contacts from Klaviyo. That ordering reflects this audience. Weigh the same table differently and the answer changes.
Side by side
| Feature | Customer.io | Klaviyo |
|---|---|---|
| Free tier | No permanent free tier; trial only | 500 emails to 250 contacts |
| Starts at | $100/mo (Essentials) | $45/mo for 5,000 emails |
| DX score | 7/10 | 6/10 |
| Deliverability | Good; reputation managed at the workspace level with optional dedicated IPs. | Solid for ecommerce traffic. |
| SDKs | node, python, go, ruby, php, java | node, python, php, ruby |
| Webhooks | Yes | Yes |
| Tagline | Behavior-driven lifecycle messaging. | Ecommerce-focused marketing automation. |
| Pricing model | subscriber-based | subscriber-based |
| API | Yes | Yes |
| SMTP | No | No |
| Templates | rich | rich |
| React Email | No | No |
| Inbound | No | No |
| Multi-tenant | Yes | No |
| Idempotency | No | No |
| Dedicated IP | Yes | Yes |
| Best for | B2B SaaS teams running complex onboarding and lifecycle programs. | Shopify and ecommerce teams. |
Customer.io
- ›Best-in-class behavioral targeting
- ›Strong workflow editor
- ›Multi-channel
- ›Expensive starting price
- ›Overkill for pure transactional
- ›Pricing scales with users
Klaviyo
- ›Ecommerce integrations are deep
- ›Predictive analytics
- ›Weak for non-ecommerce use cases
- ›Pricing climbs fast with contact growth