Generate & manage API keys

API keys authenticate your requests to the Letterhead API. A key is company-level: one key reaches every newsletter in your account, which is what integrations like Zapier use. Generating and managing keys is an admin task — if you don’t see the option, ask an administrator.

Generate an API key

1. Log in to your Letterhead dashboard and go to Settings → API Keys.
2. Click + Generate new key.
3. Enter a descriptive name using only letters, numbers, hyphens, and underscores (e.g., “zapier-integration”, “wordpress-connection”) so you can recognize the key later, and click Save.
4. Copy the key and store it securely, then paste it into the integration that needs it.

If a key stops working — for example, an integration starts returning API-key errors — return to Settings → API Keys, generate a brand new key, and update your integration with the new secret.

Key security best practices

• Treat API keys as secret — never commit them to version control or share them.
• Rotate periodically — generate fresh keys and retire old ones.
• Use different keys for different integrations — so you can replace one without breaking others.
• Review your key list periodically — and retire any you no longer use.

Next steps

• Using the Letterhead API
• Connect AI tools to Letterhead via MCP