100

Continue

Official

The customer can continue the request

General explanation of the 100 status code

The HTTP status code 100 Continue is an element in web communication that facilitates the dialog between a browser and a web server. Imagine your browser knocking on the door of a web server and starting to present a request. Before it sends the entire request, it waits for some kind of consent from the server. Code 100 Continue is just that consent, where the server signals, "I heard the beginning of your request, go ahead." Although this code is not commonly used in modern web development, as current technologies favor more efficient methods of communication, it serves as a reminder of how the web was originally designed to ensure smooth communication between the server and the end user.

Specification of the HTTP status code 100

The 100 Continue status code indicates that the initial part of a request has been received and has not yet been rejected by the server. The server intends to send a final response after the request has been fully received and acted upon. When the request contains an Expect header field that includes a 100 Continue expectation, the 100 Continue response indicates that the server wishes to receive the request payload body. The client ought to continue sending the request and discard the 100 Continue response. If the request did not contain an Expect header field containing the 100 Continue expectation, the client can simply discard this interim response.

Source / Quote by: The 100 Continue HTTP Status Code is specified by section 6.2.1 of RFC7231.

HTTP-Protocol

HTTP/1.1 (1999)

HTTP/2 (2022)

HTTP/3 (2022)

How to throw a 100 statuscode with PHP?

To throw the HTTP status code 100 on a web page, the PHP function http_response_code can be used. The syntax is as follows: http_response_code(100) (PHP 5 >= 5.4.0, PHP 7, PHP 8)

Test the 100 HTTP status code

http-statuscode.com (Test Status code 100)

httpstat.us (Test Status code 100)

In order to be able to display the HTTP status code (in this case 100 Continue) 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:

Overview
URL: https://http-statuscode.com/errorCodeExample.php?code=100
Status: 100 Continue
Those: Network
IP address: XX.XX.XX.XX

Browser compatibility of the 100 status code

Chrome	Yes
Edge	Yes
Firefox	Yes
Opera	Yes
Safari	Yes
Chrome Android	Yes
Firefox for Android	Yes
Opera Android	Yes
Safari on iOS	Yes
Internet	Yes
WebView Android	Yes

What SEO impact does the 100 status code have?

Generally, the status code 100 Continue has no direct SEO effects. It neither influences the indexing of a website by search engines nor its ranking. Primarily, it serves the communication between server and client.

User experience and SEO:

While the code 100 Continue in itself does not play a role for SEO, the user experience (UX) is a crucial element in search engine optimization. If a website experiences loading delays or other issues due to the use of status code 100 Continue, it could negatively impact the user experience. A troubled UX can lead to higher bounce rates, which in turn can impact search engine rankings.

Real world application:

In the current web environment, status code 100 Continue is rare. Modern websites and applications typically use more efficient methods to send and receive data. However, if a server is found to be issuing this status code on a regular basis, it is a good idea to review the website performance and user experience to identify potential issues.