Email API alternatives compared
There is no single best email API — there is a best one for your constraints. These pages compare Unitpost against the six providers we can import from directly, using real capability data rather than feature-checklist marketing, and each one says plainly where the other provider is the better choice.
Compare with Unitpost
- Unitpost vs ResendA developer-first transactional email API, known for the cleanest DX in the category and for React Email.Free tier: 3,000 emails/month · We lead 9, they lead 2
- Unitpost vs SendGridThe Twilio-owned incumbent, processing billions of emails a month across transactional and marketing with deep enterprise tooling.Free tier: None — a 60-day trial at 100 emails/day, then a paid plan (their free tier was retired in 2025) · We lead 8, they lead 4
- Unitpost vs PostmarkA transactional-only specialist with the strongest deliverability and time-to-inbox reputation in the category.Free tier: 100 emails/month · We lead 8, they lead 1
- Unitpost vs MailgunSinch-owned email infrastructure aimed at developers, with strong validation and deliverability tooling.Free tier: 100 emails/day on the trial · We lead 7, they lead 3
- Unitpost vs BrevoAn all-in-one marketing platform (formerly Sendinblue) covering email, SMS, chat, and CRM, with a transactional API alongside.Free tier: 300 emails/day (~9,000/month) · We lead 7, they lead 3
- Unitpost vs LoopsA modern, design-led email platform aimed at SaaS companies, focused on marketing sequences and lifecycle email.Free tier: Limited free plan by contact count · We lead 7, they lead 2
Head-to-head comparisons
Comparisons between other providers, for when we are not the question you are trying to answer.
- Resend vs SendGridResend vs SendGrid — free tiers, pricing shape, API design, and deliverability posture compared, with an honest note on where each one wins.
- Resend vs PostmarkResend vs Postmark — free tiers, pricing shape, API design, and deliverability posture compared, with an honest note on where each one wins.
- SendGrid vs MailgunSendGrid vs Mailgun — free tiers, pricing shape, API design, and deliverability posture compared, with an honest note on where each one wins.
- Postmark vs SendGridPostmark vs SendGrid — free tiers, pricing shape, API design, and deliverability posture compared, with an honest note on where each one wins.
Choosing an email provider
What is the best transactional email API?
It depends on what you optimise for, and any honest answer says so. Postmark has the strongest deliverability reputation for critical transactional mail. Resend has the cleanest developer experience and the largest modern community. SendGrid is cheapest at high volume and the only one with mature sub-account support. Brevo has the most generous free tier and real multi-channel sending. Unitpost is the pick when you want transactional and marketing in one product with unlimited contacts and one bill.
Which email providers have a permanent free tier?
As of mid-2026: Unitpost offers 3,000 emails a month, Resend offers 3,000 a month, Brevo offers about 9,000 a month (300/day), Postmark offers 100 a month, and Mailgun is trial-only. SendGrid retired its free plan in 2025 and now offers a 60-day trial at 100 emails a day before requiring payment.
Can I migrate my email provider without downtime?
Yes. Unitpost's Migration Assistant reads from Resend, SendGrid, Mailgun, Postmark, Brevo, or Loops with a read-only API key and previews everything before writing anything. Your current provider keeps sending throughout, so you cut over only once your domain is verified here. Expect to re-verify domains with new DKIM keys and regenerate webhook signing secrets — those cannot be copied between providers.
Do I need separate tools for transactional and marketing email?
Not necessarily, though the deliverability argument for separating them is real: marketing complaints can damage the reputation your password resets depend on. Unitpost keeps them in one product but separates them logically — marketing sends always carry non-removable unsubscribe headers and a footer, and one-to-many marketing sends are refused on the transactional API. If you want physical separation instead, Postmark's message streams are the strongest version of that model.
Try Unitpost on the free tier
3,000 emails a month, no credit card. Preview a migration from your current provider before you move anything.