Specification of the HTTP status code 203
The 203 Non-Authoritative Information status code indicates that the request was successful but the enclosed payload has been modified from that of the origin server's 200 (OK) response by a transforming proxy (Section 5.7.2 of [RFC7230]). This status code allows the proxy to notify recipients when a transformation has been applied, since that knowledge might impact later decisions regarding the content. For example, future cache validation requests for the content might only be applicable along the same request path (through the same proxies).
The 203 Non-Authoritative Information response is similar to the Warning code of 214 Transformation Applied (Section 5.5 of [RFC7234]), which has the advantage of being applicable to responses with any status code.
A 203 Non-Authoritative Information response is cacheable by default; i.e., unless otherwise indicated by the method definition or explicit cache controls (see Section 4.2.2 of [RFC7234]).
Source / Quote by: The 203 Non-Authoritative Information HTTP Status Code is specified by section 6.3.4 of RFC7231.
How to throw a 203 statuscode with PHP?
Test the 203 HTTP status code
In order to be able to display the HTTP status code (in this case 203 Non-Authoritative Information) and other information on the client side, the development console must be opened with F12. Afterwards you have to navigate to the tab "Network". Now you can open the page, in the network tab you should see the web page (example index.php). This must be selected and then the Herder section must be selected. Here the user will see the following result:
Browser compatibility of the 203 status code
|Chrome Android||no data|
|Firefox for Android||no data|
|Opera Android||no data|
|Safari on iOS||no data|
|WebView Android||no data|