HTTP status code

The HTTP 226 status code stands for "IM Used" (Instance Manipulations Used). It is a successful response indicating that the server has fulfilled a request for a resource and applied instance manipulations (IM) to return a modified version of the response.

When is HTTP 226 Used?

• Used when a delta encoding or transformation has been applied to a resource before sending it to the client.
• Typically used in efficient data synchronization, where only the differences (rather than the full resource) are sent.
• Helps optimize network performance by reducing bandwidth usage.

Example Scenarios

• Incremental Data Updates – The client requests only changes since the last version.
• Optimized Resource Delivery – The server compresses or modifies content before responding.
• WebDAV Synchronization – When syncing large datasets, only the necessary differences are transmitted.

Example

Client Request (Asking for a Modified Response)

    
        GET /document.txt HTTP/1.1
        Host: example.com
        IM: delta
    

Server Response (Returning Only Changes)

    
        HTTP/1.1 226 IM Used
        Content-Type: text/plain
        IM: delta

        (changes applied to the document...)
    

Summary

HTTP 226 means the server successfully processed the request and applied instance manipulations to return an optimized version of the response, rather than the full resource. It is useful for incremental updates and efficient data synchronization.