Two transactional email providers, compared on price, features and ratings, so you can pick fast.
Customer.io wins developer experience and sending APIsOneSignal Email wins price
Updated August 2026
At a glanceCustomer.ioOneSignal Email
Cost per 1k @ 100k—$1.39
G2 rating4.44.7
Trustpilot3.22.6
Drag-and-drop editorYesYes
THE VERDICT
Customer.io wins on developer experience and sending APIs. OneSignal Email wins on price.
Customer.io and OneSignal Email take different pricing approaches. OneSignal Email rates higher with developers (4.7 vs 4.4 on G2). Pick based on volume and team, and the scorecard below breaks down where each one leads.
Which should you choose?
Pick Customer.io
✓You need behavior-triggered lifecycle messaging across email, push, and SMS
✓You want journeys driven by real-time user/event data and a unified profile
✓You're consolidating marketing automation and transactional messaging
✓You need EU data residency or HIPAA-grade compliance
Pick OneSignal Email
✓You already use OneSignal for push or in-app and want to add email from the same dashboard
✓You want a free tier to start sending marketing or transactional email
✓You need to manage subscribers across push, in-app, and email in one place
✓You want a simple setup rather than a dedicated deliverability or template platform
Winner cells are tinted, green where Customer.io leads, violet where OneSignal Email does.
capability
Customer.io
OneSignal Email
Pricing
Starting paid plan
$100/mo
$19/mo
Cost per 1k @ 100k
—
$1.39
Pricing model
Subscription
Hybrid
Overage
Profile-based pricing: additional profiles $0.009 each; additional emails $0.12 per 1,000 over the plan's bundled allowance; AI credits $10/100K. Email volume does not map to a per-email tier.