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Is there a way I can simulate various connection speeds from within Firefox?

I need to be able to check http://localhost with varying speeds.

I know there are standalone applications that can do this, but I'd rather do this inside Firefox via a plugin or similar.


migration rejected from May 15 '15 at 18:28

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closed as off-topic by random May 15 '15 at 18:28

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By slow do you mean low bandwidth or high latency? – Chris Upchurch Feb 3 '09 at 0:21
See also… – che Jan 17 '14 at 9:46

Chrome has network throttling in device mode:

enter image description here

The nice thing about it is that it has presets for common situations, such as 3G. The device mode can be activated by clicking the phone icon in dev tools, circled in the screenshot.

Had a bit of a play around with that setting in Chrome Canary, it is useful though it being Canary, the developer tools aren't particularly stable (at least not for me). – Turnerj Sep 9 '14 at 0:01
This is now in the Chrome stable – jao Oct 21 '14 at 7:29
I love you! This is the best method if you don't know how to work with netem on linux. – Eduard Luca Dec 8 '14 at 16:23
Doesn't work in upload: – Ich Jun 29 '15 at 15:20
@Ich thanks for the heads-up – Mihai Rotaru Jun 29 '15 at 18:30

For OS X, check this:


enter image description here

speedlimit is a Leopard preference pane for limiting your network bandwidth to one of a couple different speeds—768k DSL, Edge, 3G, and Dialup. This is really handy for testing your iPhone app under normal Edge network conditions in the iPhone Simulator. The new version allows you to restrict the slowdown to only a specific set of hosts.


For OS X, Apple offers a System Preference preference pane for download in their Developer Center called Network Link Conditioner, which is able to simulate low bandwidth, high delay, and packet loss.


How to download (from here):

First, you’ll want to get the Hardware IO Tools for Xcode. To do this, go into the Xcode menu, then choose “Open Developer Tool” and finally “More Developer Tools…”. You’ll be taken to Apple’s developer downloads site; you should download the “Hardware IO Tools for Xcode”.

Or (as of Jan 2014) go to, Resources, OS X, Additional Downloads, then filter for Developer Tools.

This should be available for all registered developers and not need one of the memberships.


protected by studiohack Dec 3 '11 at 3:01

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