You can use API keys to call public APIs.
Generating API Keys
Go to the Admin panel.
Click on API keys.
Click on the Add API key button. The Add new API key pane opens.
Enter a Name for the API key.
If a Type option is shown, choose General. The Zapier type is only for the Zapier integration.
Pick an Expiry date, or check Never expires if the key should not expire.
Click Save changes.
Copy the key from the API keys list using the copy icon. The key stays in the list, so you can copy it again later.