Installing the Fiddler certificate authority in Firefox

Environment

Product
Product Version	Fiddler Everywhere 1.0.0 and above
OS	Linux, macOS, Windows

Description

Q: How can I manually install the Fiddler's Certificate Authority (CA) in Firefox?

Q: I want to capture and decrypt traffic only from a browser. Can I export and install the Fiddler CA in Firefox certificate store?

Q: I don't want to install the Fiddler CA in my operating system certificate store. Insteasd, I wanto to export and install the Fiddler CA in Firefox certificate store. Is that possible?

Solution

1. Export the Fiddler CA to your Desktop folder through the options in Settings > HTTPS > Advanced > Export Fiddler CA.

2. Open Firefox.

3. Go to Settings > Privacy & Security.

4. Click the View Certificates button to open the Firefox's Certificate Manager.

5. Within the Certificate Manager, select the Authorities tab.

6. Click the Import... button and choose the Fiddler_Root_Certificate_Authority.crt file from your Desktop folder.

7. Select the Trust this CA to identify websites. checkbox and click OK.

The Fiddler CA is now installed. You can now decrypt traffic captured from the Firefox browser.

In addition to installing and Fiddler CA, you can also instruct Firefox to explicitly use the Fiddler Everywhere proxy through Settings > General > Network Settings > Manual Proxy COnfiguration and then set the Fiddler address and port (by default, IP 127.0.0.1 and port 8866) as values for HTTP Proxy and HTTPS Proxy fields.