Set External Source Viewer in Firefox, Opera and Internet Explorer

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If you prefer to view webpage source in an external viewer or editor, rather than the default one, this post is for you. Following some steps you can set an external source viewer for Mozilla Firefox, Opera and Internet Explorer.

Mozilla Firefox

  1. Open Firefox configurations page, by typing in about:config in the address bar.
  2. In the “Filter” field, enter view_source.editor.external and set its value to true.
  3. Next, again in the “Filter” field, type in view_source.editor.path. Double-click on the result, and enter the full path to the source viewer application you want to use.

That’s it! Restart Firefox to use the new viewer.


  1. Go to Menu > Settings > Preferences, or press Ctrl + F12.
  2. In the Preference window, click on “Advanced” Tab, and find and click on Programs in the left pane.
  3. Next, click on the “Edit” button under “Choose Application for viewing source” options.
  4. Select “Open with another application” and browse to the editor you want to use, or just type in its path.
  5. Click OK to save changes.

Changes take effect immediately.

Internet Explorer

  1. Open Registry Editor and navigate to the following key:
  2. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer
  3. Create a new key called “View Source Editor.”
  4. Under “View Source Editor,” create another key and name it “Editor Name”.
  5. Double click on the (Default) value of “Editor Name” key and enter path to the editor you want to use.
  6. Restart Internet Explorer to activate change.

This also works with the latest Internet Explorer 9.