HAR

HAR (HTTP Archive) is a format based on JSON for saving a record of a Web access, including the HTTP request and response headers used to retrieve a document, and timing information on how long each part took to load. They can be used in server analysis and in archiving of Web data. HAR files are required to be encoded in the UTF-8 character encoding.

.har files are raw HAR, while .harp files are HAR enclosed in a callback function for use as JavaScript code.

Specs

 * Official spec, at W3C
 * HAR 1.2 spec, at Software is hard

Utilities

 * HAR viewer (Software is hard)
 * harviewer (Google Code)
 * Chrome HAR viewer

Other links

 * Wikipedia article
 * What is a HAR File and what do I use it for?