Developer-focused email APIs for sending password resets, receipts, and product notifications reliably. We compare Resend, MailerSend, Plunk, and Loops on deliverability tooling, developer experience, and price per thousand emails.
4 tools · Last updated June 11, 2026
| Tool | Best for | Pricing | Free plan | Open source | Why choose it |
|---|---|---|---|---|---|
 Resend | Developers integrating email into SaaS products | Freemium · from $20/mo | Best developer experience — React Email templates and clean SDKs for every major language. | ||
 MailerSend | Product teams where non-developers manage email templates | Freemium · from $28/mo | Transactional email with a drag-and-drop template editor non-developers can use. | ||
 Plunk | Indie hackers and bootstrapped SaaS founders | Freemium · from $0.001/email | Open source and usage-based (~$0.001/email) — cheapest at low volume, self-hostable. | ||
 Loops | SaaS startups consolidating email tools | Freemium · from $49/mo | Combines transactional and lifecycle email for SaaS in one tool with a notion-like editor. |
The email API for developers — send transactional and marketing email that reaches inboxes, not spam folders.
Transactional email service built for teams — send via API or SMTP with drag-and-drop templates and strong deliverability.
Resend has the best developer experience right now — React Email templates, clean SDKs, and a generous free tier of 3,000 emails per month. MailerSend is the stronger pick if non-developers on your team also need to edit templates.
Transactional email is triggered by user actions (signups, receipts, alerts) and sent one-to-one through an API; marketing email is sent in bulk to lists. Separate the two streams — mixing them on one domain hurts the deliverability of your critical transactional mail.
Entry paid plans run $20-28 per month for 50,000 emails (Resend, MailerSend), while usage-based options like Plunk charge per email sent (around $0.001), which is cheaper at low volume. All four offer free tiers good for roughly 3,000 emails a month.
