HTTProbe is a powerful HTTP sniffer and analyser written in Java.

Its principal function is to display the HTTP headers of the request sent by a HTTP client and the response answered by a HTTP server. To display HTTP headers, HTTProbe must act as a pseudo-proxy server to which HTTP clients send their request. Thus, any HTTP client application like Internet Explorer, Mozilla or Opera which can connect to a proxy server can have their HTTP requests spied by HTTProbe.

For testing and debugging purpose, HTTProbe allows the user to resend a HTTP request after having optionally modify the HTTP request's HTTP header. Any modification made to the request's HTTP header can be compliant or not with the HTTP/1.1 protocol depending on the user's interface used. The response of a resent request is accessible like any other response expect that it is not sent back to the browser. For Windows, this response can be visualized directly in the default browser for html, jpeg, gif and png content type. Otherwise, the response can be visualized in a text area.

HTTProbe can filter the request/response pairs kept for further analysis based on the request method, the response’s content type and the response’s status. The filtering doesn’t affect the request/response pairs communicated between a HTTP client and a HTTP server but only which pair is available for further analysis.

The request, the response or both can be logged. For the response, it is possible to log only the HTTP header while for the request the HTTP header and the HTTP body are automatically logged.