HTTP sniffer is an application that monitors traffic data to and from a computer network link. It can be an independent software application or hardware device equipped with the relevant firmware and software.

Sniffers exist in a variety of platforms including both commercial and open source versions. Some sniffers can only intercept data from TCP/IP protocols but the more complex ones even capture and decode data packets for the more secure SSL /HTTPS protocol that use asymmetric cryptography.

Types of Sniffers

Sniffers come in a variety of forms and the major ones include online, proxy, and application sniffers.

Online HTTP sniffers are limited to basic analyzing of a particular webpage. You provide a link to check and they respond with the HTTP header and HTTP content of the requested page. Online sniffers can be used to quickly check the basic server settings and see the source code of the requested page.

Proxy sniffers monitor all traffic between internet applications, including your web browser and the web on certain protocols like HTTP or HTTPS. These HTTP sniffers can only operate with applications configured to use proxy servers and unlike other sniffers, these may have an effect on the traffic. Proxy HTTP sniffer may decode SSL / HTTPS traffic, but developers need to install a special self-signed root certificate issued by the proxy vendor. This certificate is needed to implement the Man-in-the-middle technique for decrypting SSL.

Application sniffers are the most powerful ones. They are standalone applications that work on a developer’s computer and have the ability to capture network traffic for all protocols. A packet sniffer can even capture data packets from other computers in the same network. Application HTTP sniffer is not limited to Man-in-the-middle technique when decrypting the SSL / HTTPS traffic as a proxy sniffer. It may use API hooks for decoding SSL and don’t require root certificate to operate. But API hooks have limited usage, for example, API hooks don't work with recent versions of Google Chrome or Opera. HTTP Debugger is an example of application HTTP sniffer. Versions prior to v5.0 were using API Hooks for decoding SSL while new versions use Man-in-the-middle technique.

HTTP Sniffers for Developers

Modern browsers provide some basic information about website traffic usage (for example for Google Chrome you can see this information on Network tab of Web Inspector). This information, though, is limited and not easy to analyze.

HTTP sniffers, however, provide in-depth information on every aspect of loading a webpage and/or any web resource including but not limited to built-in HTML, CSS, JS, JSON, XML syntax highlighters, JSON and XML tree structure viewers, built-in image viewers, automatic server error and performance bottlenecks detecting and even website structure tree viewer. With some sniffers, you can modify and reply back modified HTTP requests to the web server to test it with various conditions in order to reproduce and fix website errors.

Some advanced HTTP sniffers can visualize your traffic in the form of charts or diagrams and generate HTTP traffic reports.

HTTP Sniffers for Security Analyzing

Network and System Administrators use network sniffer software to monitor and troubleshoot the network traffic. For example, administrators may use our http analyzer to see the HTTP data packets sent by malware programs and identify the security risks or to detect undesirable activities and maintain effective network data flow.

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HTTP Debugger is a proxy-less HTTP analyzer for developers that provides the ability to capture and analyze HTTP headers, cookies, POST params, HTTP content and CORS headers from any browser or desktop application. Awesome UI and very easy to use. Not a proxy, no network issues!
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