The URL
https://sheets.googleapis.com/v4/spreadsheets/[ID_OF_SPREADSHEET]?key=[MY_API_KEY]
What I get
{
"error": {
"code": 403,
"message": "The caller does not have permission",
"status": "PERMISSION_DENIED"
}
}
At the moment, I have no Key Restriction on my API Key for the sake of testing.
I've had a look at a past question that's been popular but no luck.