Zapier Basic Authentication Not Sending POST Data Correctly

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1

I’m working on building a custom integration in Zapier and running into issues with Basic Auth setup. When I test the authentication step, it seems like the POST parameters aren’t being transmitted properly to my API endpoint.

Here’s what I’ve configured:

  • Selected Basic Auth as the authentication method
  • Set up POST endpoint for authentication
  • Mapped username and password fields using {{bundle.authData.username}} and {{bundle.authData.password}}
  • API works perfectly when tested in Postman with same credentials

The problem is that my API receives empty or null values for the authentication parameters when called through Zapier. My endpoint returns a password validation error, which suggests the data isn’t reaching the server correctly.

// Expected API response when credentials are valid
{
  "user_data": {
    "name": "John",
    "surname": "Smith", 
    "email": "[email protected]",
    "mobile": "9876543210",
    "account_id": "8pjB****",
    "access_token": "yMlzU***"
  },
  "require_email_verification": false,
  "success": true,
  "response_message": "Authentication successful!"
}

// What I'm actually getting from my API
{
  "require_email_verification": false,
  "success": false,
  "response_message": "Password must include lowercase, uppercase, and numeric characters"
}

Is there something wrong with how I’m setting up the POST method for Basic Auth in Zapier? Should I switch to GET method instead, or am I missing a crucial configuration step?

2

Looks like you’re hitting a common Zapier issue with Basic Auth. When you use POST, the credentials often don’t get formatted right for your API - that’s why you’re seeing empty values. Try switching to GET instead since Basic Auth credentials usually go in the headers anyway. If you absolutely need POST, you’ll have to set up custom auth and manually base64-encode the credentials in the Authorization header. Also double-check that your API actually expects Basic Auth and not just regular form fields.

3

Had the same headache with Basic Auth in Zapier about six months back. This usually happens when Zapier’s not encoding your credentials properly in the Authorization header - it’s sending them as POST body parameters instead. Basic Auth needs credentials in the header as a base64 encoded string, not form data. Check your API endpoint setup. Your server might be expecting credentials in the Authorization header format (Authorization: Basic base64encodedcredentials) rather than POST parameters. Also double-check that your auth test is hitting the right endpoint URL. Make sure there aren’t any trailing slashes or path mismatches between your Zapier config and what your API wants. That password validation error means your API’s getting something, just not the actual password.

4

zapier’s basic auth gets weird with post requests. it usually dumps your username/password into the request body instead of the authorization header where it belongs. skip their basic auth and build your own - just base64 encode it manually with btoa(username + ':' + password) and stick it in the header yourself. fixed the same issue for me last year.