HAR File

The HTTP Archive format - HAR - is a JSON-formatted archive file format for logging of a web browser's interaction with a site. The common extension for these files is .har.

Typically data about timings is stored and can be used to generate a waterfall graph:

• Time to fetch DNS information
• Time for each object request
• Time to connect to server
• Time to transfer assets from the server to the browser of each object

HAR files can be generated by most browsers.