Postmark 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 Postmark Server Token with the email sending endpoint
Data verified 2026-07-13
Key format & how to get one
1. Visit https://account.postmarkapp.com/ and sign up/login 2. Go to Servers > Your Server > API Tokens 3. Copy your Server Token (starts with 'server-') 4. Ensure your sender signature is verified 5. Free tier: 100 emails/month
Cannot test this key from your browser
This provider blocks in-browser requests or requires a server-side secret. Test it from a terminal instead:
curl -sS -X POST https://api.postmarkapp.com/email -H 'Accept: application/json' -H 'Content-Type: application/json' -H 'X-Postmark-Server-Token: {{KEY}}' -d '{"From":"test@example.com","To":"test@example.com","Subject":"Test Email","TextBody":"Hello world!","HtmlBody":"<html><body><strong>Hello</strong> world!</body></html>","MessageStream":"outbound"}'Related tools
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