404 Checker
HTTP Status Codes
4 Codes Documented
1XX — Informational
Interim responses indicating that the initial part of the request was received and the client can continue sending data or wait for a final response.
HTTP
100
Continue
RFC 9110
The 100 Continue status is an interim response indicating that the initial part of the request has been received and no errors have been detected. In standard HTTP client-server interactions, it is issued in response to a client's "Expect: 100-continue" request header, confirming that the client should proceed to send the remaining request payload. The server must issue a final response once the full request is processed.
HTTP
101
Switching Protocols
RFC 9110
The server accepts the client's request to switch protocol as requested via the "Upgrade" request header. A primary modern example is upgrading an HTTP/1.1 connection to a full-duplex WebSocket connection.
HTTP
102
Processing
RFC 2518
An interim status code used in WebDAV environments to inform the client that the server has accepted the complete request, but has not yet finished processing it and no response is currently available. This prevents the client from timing out during long-running tasks.
HTTP
103
Early Hints
RFC 8297
Primarily used with the "Link" header to allow user agents to begin preloading critical subresources (CSS stylesheets, JavaScript modules, web fonts) while the origin server generates the final primary HTML response.
Verify Status Codes in Real-Time
Encountered an unexpected HTTP response on your website? Use our free tool to inspect the full header and status chain.
Launch 404 Checker