Free Email APIs for Developers: 9 Options and Their Real Daily Limits

Your app needs to send a password reset email. Maybe a receipt, a magic link or a "someone replied to your comment" note. You cannot do that from your own server without landing in spam, so you hand the job to an email API. The free plans for these look similar on the pricing page and behave very differently once real users show up.

Two numbers matter most: the monthly allowance and the daily cap. A plan that offers 3,000 emails a month but caps you at 100 a day is really a 100 a day plan. Here are nine that cost nothing, sorted by what they let you do on day one.

The quick comparison

• Mailjet: 6,000 a month, 200 a day
• Mailtrap: 4,000 a month, 150 a day
• Resend: 3,000 a month, 100 a day
• Brevo: about 300 a day (confirm in your account)
• Mailgun: 100 a day
• Plunk: 1,000 a month
• MailerSend: 500 a month
• EmailJS: 200 requests a month
• Postmark: 100 a month

Best for most side projects

Resend

The free plan gives you 3,000 emails a month, with a cap of 100 a day. You also get 3 domains, 3 inboxes, a webhook endpoint with all events and 30 days of data retention. Open and click tracking is a per domain setting on every plan. The daily cap is the catch: if you launch and 400 people sign up in a morning, 300 of those welcome emails wait until tomorrow. Reviewers also mention that DNS setup is a little tricky. See Resend.

Mailtrap

The Email API and SMTP plan allows 4,000 emails a month, up to 150 a day, with no credit card. Templates, webhooks and inbound email are included. The weak spot is logs, which last only 3 days, so a delivery problem from last week will be hard to trace. Mailtrap also has a separate sandbox for testing, with 50 test emails a month, which is handy while you build. Details on Mailtrap.

Mailjet

The most room on paper: 6,000 emails a month, 200 a day, 1,000 contacts, APIs, SMTP relay and webhooks, no card needed. One Capterra reviewer reported a suspension for suspected spam without notice, and delays on password reset emails. That is a single report, but it is worth knowing before you build your login flow on it. Read the Mailjet listing.

Brevo

Free forever, no card, and the daily cap is about 300 emails according to G2. The Brevo pricing page does not print that number, so check it in your account before you plan around it. Removing the Brevo branding costs $10.80 a month as an add on. A Reddit commenter says it works well for transactional email on the free tier. See Brevo.

Smaller or stranger free plans

Mailgun

100 emails a day, 2 API keys, 1 day of logs and 1 inbound route. It is the one that makes debugging hardest, since a day of logs means last week's bug is gone. Card rules are unclear: the help center says no card is needed, while the sign up page and one Reddit comment say otherwise. Confirm when you register. See Mailgun.

Plunk

1,000 emails a month, unlimited contacts, workflow automation, broadcasts, inbound email and email validation, with Plunk branding on free emails. You can also host it yourself with Docker Compose. A Hacker News commenter points out that a self hosted install still needs a cloud service to do the sending. See Plunk.

MailerSend

500 emails a month, 1 template, 1 domain, 100 API requests a day and 1 day of activity data. It asks for a credit card on the Free plan (you are not charged) and the account must be approved before you can subscribe. If you want something with no friction, look elsewhere. See MailerSend.

EmailJS

This one sends email straight from the browser, no backend required, which suits a static portfolio with a contact form. Free means 200 requests a month and 2 templates, and once you hit the limit extra requests are dropped. No overage bill, but no email either. See EmailJS.

Postmark

The free Developer plan gives you only 100 emails a month, with a REST API, SMTP, a sandbox mode and event webhooks. It never expires and does not allow overages. There is no tier between 100 and 10,000 emails, so the first step up in price is a big one. Good for testing deliverability, tight for a live app. See Postmark.

Which one should you pick

• A normal app with signups and resets: Resend or Mailtrap.
• Need the highest monthly allowance: Mailjet, with the support warning in mind.
• A static site with a contact form: EmailJS.
• Want to self host: Plunk.
• Only testing deliverability: Postmark.

Before you ship, send yourself a password reset from a Gmail and an Outlook address and check the spam folder. Then set up SPF, DKIM and DMARC records for your domain, since every provider above needs them to deliver reliably. A free plan that lands in spam is not a plan.