Identifying Upstream Status Codes

When perform an HTTPS request using the VGS HTTPS Proxy, VGS will always attempt to forward the status code that it receives from the upstream server. That said, it is hypothetically possible that the VGS system can provide a different response code than what was returned from the third-party.

In order to verify that the upstream server and VGS are returning the same response codes, VGS appends a "VGS-Upstream-Status-Code" header to the HTTP response. This value contains the exact response code that VGS received from the upstream service and should always match the actual HTTP response status code.

The following is a diagram showcasing how the status code is used during an HTTPS request through the VGS proxy.

Sample Response

Below is an example of an HTTPS request that is proxied through the VGS Outbound Route. The response shows both the "200" response from VGS, and the VGS-Upstream-Status-Code of "200" that VGS received from the upstream.

curl -i https://echo.sandbox.verygoodvault.com/post --cacert sandbox.pem \
  -x https://$VGS_USERNAME:@[email protected]:8443  
  
HTTP/1.1 200 Connection established
Connection: keep-alive
Via: 1.1 proxy

HTTP/1.1 200 OK
Date: Tue, 13 Jan 2026 06:28:17 GMT
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, POST, PUT, DELETE, PATCH
content-length: 0
VGS-Upstream-Status-Code: 200
Via: 1.1 proxy
VGS-Request-Id: b7415b02f87edf0b2e89448b6dd578c5