Network monitor - view the HTTP headers of the current page, or globally, from all tabs. You can use it at any time, also after the page has loaded.

Netmon promo image
What is Netmon?

Netmon is a Firefox add-on that serves as a network monitor. It enables you to view the HTTP headers of the current page or globally from all tabs, even after the page has loaded. With the ability to track past requests and display the current count of requests in any given tab, Netmon is an indispensable tool for diagnosing random errors and analyzing network activity.

Users: 185 ▲ 1
Rating: 4.50 (4)
Version: 1.0 (Last updated: 2019-05-06)
Creation date: 2019-05-06
Weekly download count: 5
Firefox on Android: No
Risk impact: High risk impact
Risk likelihood: Low risk likelihood
Manifest version: 2
  • storage
  • activeTab
  • tabs
  • webNavigation
  • webRequest
  • webRequestBlocking
  • http://*/
  • https://*/
Size: 1.78M
URLs: Website
Stats date:

Other platforms

Not available on Chrome
Not available on Edge
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Network monitor - view the HTTP headers of the current page, or globally, from all tabs. You can use it at any time, also after the page has loaded.

This is useful when there are random errors in some cases and you just want to see what happened, list the past requests.

It also constantly displays current count of requests in any given tab.

It's open source

If you have any suggestions, please don't hesitate to reach me on or file an issue on the github page above.

User reviews
First.. Thank you so much for making this! Made my life a lot easier :) If I may come with some small requests, I would love to have a little more options.. - Sorting by (type, size, name, etc) - Predefined filter (type, method, size, name, etc) - Direct link to media? I have a few more, but this is what I wish the most for.. Again, thank you very much for your time making this addon possible!
by Glock, 2020-09-03

It does what it claims fine, no problem there... But 1st I'd like to be able to keep that window open while operating with the page - now pretty much wherever I click it closes. 2nd issue I have is with my small netbook - on this particular machine with fairly low resolution screen (1024x600) I tend to keep everything I don't specially want to keep quickly accessible from toolbar hidden, so I tried to pin the Netmon button to the overwflow menu, but when opened from there the window was way too narrow to be of any comfortable use. It would be nice if it opened just as wide from there as from toolbar. All-in-all a good add-on - my complaints are very small.
by robsku, 2020-02-02

あるウェブサイトがボタンクリックで新しいタブを開いた瞬間の通信を見るのに Global monitor (右上の地球アイコン)が使えました。
by criticabug, 2019-11-26
View all user reviews
Risk impact

Netmon is risky to use as it requires a number of sensitive permissions that can potentially harm your browser and steal your data. Exercise caution when installing this add-on. Review carefully before installing. We recommend that you only install Netmon if you trust the publisher.

Risk likelihood

Netmon has earned a fairly good reputation and likely can be trusted.

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