Customer.io vs Resend
Pricing
Customer.io: From $100/mo
Resend: Free up to 3,000 emails/mo, then from $20/mo
Description
Customer.io: Behavior-based email and push for SaaS
Resend: Modern email API that developers actually enjoy using
Pros
- Powerful segmentation
- Multi-channel (email, SMS, push)
- Great for product-led growth
- 3,000 free emails/month, enough for most early-stage products
- Clean, simple API that takes minutes to integrate, not hours
- Built by the creator of React Email: the DX is noticeably better than SendGrid or SES
Cons
- Expensive for small lists
- Steep learning curve
- Younger service: smaller ecosystem and fewer battle-tested edge cases
- No visual email template builder: you design emails in code (React Email)
- Deliverability is good but has not been tested at the same scale as Postmark or SendGrid
Details
Customer.io sends messages based on what users actually do in your product. Founded by Colin Nederkoorn, “fundstrapped” (took some money but runs like bootstrapped). Took 18 months to hit $10k MRR, now at $100M ARR. Great for SaaS doing product-led growth.
Resend is what happens when someone who hated the existing email APIs built a new one. Created by Zeno Rocha (who also built React Email), it focuses on developer experience above everything else. The API is clean, the docs are clear, and you can have transactional emails working in your app in about 15 minutes.
The free tier of 3,000 emails per month covers most solo founders for months. When you outgrow it, $20/month gets you 50,000 emails. If you value developer experience and clean code over the battle-tested reliability of Postmark or the scale of SendGrid, Resend is the pick.
Verified
