FCM with Postman - The request was missing an Authentication Key (FCM Token)

While the answers above are still correct, you may choose to use HTTP v1. This requires Bearer instead of key= and uses an Oauth2 access token instead of a server key string. To view HTTP v1 specifications, please refer to the link below:

https://firebase.google.com/docs/cloud-messaging/migrate-v1

Wrong:

Authorization:AIzaSyDDk77PRpvfhh......

Correct:

Authorization:key=AIzaSyDDk77PRpvfhh......

Full example:

https://fcm.googleapis.com/fcm/send
Content-Type:application/json
Authorization:key=AIzaSyZ-1u...0GBYzPu7Udno5aA

{ "data": {
    "score": "5x1",
    "time": "15:10"
  },
  "to" : "bk3RNwTe3H0:CI2k_HHwgIpoDKCIZvvDMExUdFQ3P1..."
}

The 401 error pertains that your Authorization Key is invalid or incorrect.

When using Postman, add a key= prefix for the value of Authorization, like so:

key=AAA...

See below for a tutorial on Sending Downstream FCM Messages using Postman.

Also, for your notification message payload, text isn't one of the valid parameters, I think you were looking for message instead.

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Sending Downstream Messages using Postman

To do this in Postman, you simply have to set the following:

1. Set request type to POST
2. In the Headers, set the following:
   • Content-Type = application/json
   • Authorization = < Your FCM Server Key > (See your Firebase Console's Cloud Messaging Tab)
3. Set the payload parameters in the Body (*in this example, we used the raw option, see screenshot (2)*)
4. Send the request to https://fcm.googleapis.com/fcm/send

Screenshots:

(1)

Note: Always keep your Server Key a secret. Only a portion of my key is visible here so it should be fine.

(2)

(3)

Notice that the request was a success with the message_id in the response.