Category · 13 tools · 10 comparisons
Transactional email APIs
Send application-triggered emails reliably through APIs and SMTP.
At a glance
- Tools tracked
- 13
- Entry plans
- $5.60–$20/mo
- Typical entry plan
- $12/mo
- Free plan
- 9 of 13
- Cheapest paid
- MailerSend, $5.60/mo
- Best value score
- Mailtrap, 8/10
Every tool we cover
API pricing →| Tool | Score | From | Top listed plan | Free plan | Trial | Pages |
|---|---|---|---|---|---|---|
 PostmarkPostmark | 7.8 | $15/mo | $18/mo | Yes | — | ReviewPricingAlternatives |
 MailtrapMailtrap | 7.7 | $12/mo* | $1,250/mo | Yes | — | ReviewPricingAlternatives |
 SMTP2GOSMTP2GO | 7.4 | $10/mo | $62.50/mo | Yes | — | ReviewPricingAlternatives |
 EmailJSEmailJS | 7.3 | $7.20/mo | $32/mo | Yes | — | ReviewPricingAlternatives |
 ResendResend | 7.2 | Free* | — | Yes | — | ReviewPricingAlternatives |
 MailerSendMailerSend | 7.2 | $5.60/mo* | $5.60/mo | Yes | 14 days | ReviewPricingAlternatives |
| SendPostSendPost | 7.2 | $7/mo* | $997/mo | No | — | ReviewPricing |
 MailgunMailgun | 7.1 | $15/mo | $90/mo | Yes | 30 days | ReviewPricingAlternatives |
 SparkPostSparkPost | 6.8 | $15/mo | $1,000/mo | Yes | — | ReviewPricingAlternatives |
 Mailchimp Transactional EmailMailchimp Transactional Email | 6.5 | $20/mo* | $20/mo | No | Yes | ReviewPricingAlternatives |
 Twilio SendGridTwilio SendGrid | 6.4 | $19.95/mo* | $1,099/mo | No | 60 days | ReviewPricingAlternatives |
 ZeptoMailZeptoMail | 5.8 | Custom* | — | No | Yes | ReviewPricing |
 Amazon Simple Email Service (SES)Amazon Simple Email Service (SES) | 4.0 | Free* | — | Yes | — | ReviewAlternatives |
* Lower confidence: the vendor's pricing page couldn't be read directly or didn't list every price, so the figure was compiled from other public sources and may be incomplete. Check the vendor's page before you buy.
Head-to-head
MailgunvsTwilio SendGridMailgun vs Twilio SendGrid
ResendvsTwilio SendGridResend vs Twilio SendGrid
ResendvsPostmarkResend vs Postmark
Amazon Simple Email Service (SES)vsMailgunAmazon Simple Email Service (SES) vs Mailgun
PostmarkvsMailgunPostmark vs Mailgun
MailgunvsResendMailgun vs Resend
Mailchimp Transactional EmailvsTwilio SendGridMailchimp Transactional Email vs Twilio SendGrid
Mailchimp Transactional EmailvsMailerSendMailchimp Transactional Email vs MailerSend
Twilio SendGridvsSendPostTwilio SendGrid vs SendPost
SMTP2GOvsTwilio SendGridSMTP2GO vs Twilio SendGrid
Highest scored
PostmarkPostmark
A developer-friendly hosted email API, with predictable integration and costs that rise with volume.
MailtrapMailtrap
A hosted email API, campaign service and QA sandbox with useful free tiers and plan-based limits.
SMTP2GOSMTP2GO
A managed email relay with reporting, but verify API and sending limits before production.
Transactional email APIs: quick answers
How much do transactional email apis cost?
Paid plans for the 13 transactional email apis we track start between $5.60 and $20 a month, and the typical entry plan is about $12 a month. 9 of them have a free plan. ZeptoMail doesn't publish a starting price. Prices are the vendors' own, checked Nov 10, 2026; most quote the per-month price when billed annually.
Which transactional email api is the cheapest?
MailerSend has the lowest paid entry plan at $5.60 a month, followed by SendPost at $7. If you can live with limits, Postmark, Mailtrap, SMTP2GO and EmailJS have a free plan.
Which transactional email apis have a free plan?
Postmark, Mailtrap, SMTP2GO, EmailJS, Resend, MailerSend, Mailgun, SparkPost and Amazon Simple Email Service (SES) have a free plan. Mailchimp Transactional Email, Twilio SendGrid and ZeptoMail offer a free trial instead. Free plans are usually capped on usage, seats or features; each review lists the limits.