If you followed the page, Make Your First API Call, and are getting an error response when using Postman, here are a few steps you can follow:
Note: When testing, try a more simple API call like List Countries, or List Payment Methods by Country.
1. If your error is the following: Unauthenticated API Call
{
"status": {
"error_code": "UNAUTHENTICATED_API_CALL",
"status": "ERROR",
"message": "The API received a request, but the signature did not match. The request was rejected. Corrective action: (1) Remove all whitespace that is not inside a string. (2) Remove trailing zeroes and decimal points, or wrap numbers in a string.",
"response_code": "UNAUTHENTICATED_API_CALL",
"operation_id": "1f376362-cf86-4840-976b-03219da4f4e1"
}
}
Empty Spaces in Your Values
There may be a space between the end of one of your API keys. Be sure to check for empty spaces and use the backspace and save. 
Mismatched Values
You can also check if variables and values of the rapyd_access_key and the rapyd_secret_key are flipped.
Having the Wrong Https Request
If you want to duplicate your request to save a set of body parameters outside of the collection, make sure you duplicate a similar request. Having the wrong https method can cause a UNAUTHENTICATED return.
2. If your error is the following: Missing Authentication Headers
{
"status": {
"error_code": "MISSING_AUTHENTICATION_HEADERS",
"status": "ERROR",
"message": "The request did not contain the required headers for authentication. The request was rejected. Corrective action: Add authentication headers.",
"response_code": "MISSING_AUTHENTICATION_HEADERS",
"operation_id": "514c0464-e230-4c32-a064-a0237607105e"
}
}
Do Not Edit Headers in Postman
Check if all of the header keys are correct. If you leave the headers as is when you downloaded Postman, they should be working. If you edited any header requests it may cause issues.
