What is a HAR file?

HAR is a file format used by several http;// session tools to export the captured data. The format is basically a JSON object with a particular field distribution.

Why HAR?

This will help us understand faster, what is failing in the particular session and causing the issue.

How to get the HAR file?

Internet Explorer/Edge:

Edge natively produces HAR files. See detailed instructions in the Microsoft site

  • Open the Network tool in F12 developer tools
  • Reproduce the issue
  • Export captured traffic as a HAR (CTRL + S)

For Internet Explorer, you will need to use: HttpWatch .

  • Download and Install HttpWatch
  • Start the HttpWatch capture right before reproducing the behaviour you want to study
  • Stop the HttpWatch capture right after reproducing the behaviour to study
  • Export the capture to HAR format


Starting with Firefox 41, HAR files can be created without any additional extension.

  • Start Firefox Developer Tools in Network mode (Top right menu > Developer > Network, or ctrl-shift-Q)
  • Reproduce the issue
  • Save the capture by right-clicking on the grid and choosing "Save all as HAR"
  • Export the capture to a HAR file


You can record your HTTP session using the Network tab in the Developer Tools in Chrome.
  • Open the Developer Tools from the menu (Menu > Tools > developer tools), or by pressing Ctrl+Shift+C on your keyboard
  • Click on the Network tab
  • Look for a round button at the top left of the Network tab. Make sure it is red. If it is grey, click it once to start recording.
  • Check the box next to Preserve log.
  • You can use the clear button (a circle with a diagonal line through it) right before trying to reproduce the issue to remove unnecessary header information
  • Save the capture by right-clicking on the grid and choosing "Save as HAR with Content"