Resend API Key Tester

Test any AI or API key in your browser — instantly see if it's valid, and why it isn't. Nothing is stored.

Test your Resend API key with the emails endpoint

Data verified 2026-07-13

Key format & how to get one

Prefix: re_ Example: re_abc123... Resend keys start with re_. 1. Visit https://resend.com/ and sign up/login 2. Go to API Keys section in your dashboard 3. Click 'Create API Key' 4. Provide a name and copy the generated key 5. Free tier: 3,000 emails/month

How to test

  1. Copy your key from resend.com/api-keys.
  2. Paste it above and click Test Key.
  3. Green means valid; red shows the error and fix.

Common errors

CauseFix
Invalid or revoked API key.Create a new key at resend.com/api-keys and paste it here.
The sending domain isn't verified for this key.Verify a sending domain at resend.com/domains, or use onboarding@resend.dev for tests.

Resend API docs →

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