I currently deploy with GAE (google app engine) and I try to implement some AJAX validation. So I got a couple text-fields and "spinners" (ajax loaders) which should be displayed when an AJAX request is sent. But I deploy on my local computer (localhost), so the GAE SDK reacts very fast on any request. It takes about 50-70 ms(miliseconds) to perform the whole ajax request, which is far far away from the real.

Is there a way to somehow simulate slow Internet connection? I just want to see how my "spinners" work. I want to test some ajax setting (jquery) about timeouts, errors and so on...

Any ideas ?

  • You are looking for a latency simulator. A search for that term should return something useful.
    – Anonymous
    Jun 14, 2011 at 18:01
  • what is your current internet speed? which speed do you want to have (approximately)?
    – kokbira
    Jun 14, 2011 at 18:34
  • ADSL (~ 8000 KBit/s Down). There is a nice feature in adobe's flash Player. If you develop an Pre-Loader with AS you can easy test it in flash player with different speed (kind of Dual-Up, ISBN and DSL 1000 simulation)
    – V-Light
    Jun 14, 2011 at 19:49

5 Answers 5


If you use a browser to simulate that, you can use Firefox Throttle, Internet Explorer Throttle or Fiddler.

  • Fiddler did the trick. At least i was able to test the AJAX request @ Dual-Up Modem Speed.
    – V-Light
    Jun 14, 2011 at 21:39
  • Link [1] is dead
    – tuxayo
    Jul 26, 2017 at 18:04
  • @tuxayo, thank you. The same occurred to link [2] (now it points to a hosting service - it normally happens when the domain is abandoned). I asked meta.stackoverflow.com about it and I'll correct the answer later.
    – kokbira
    Jul 31, 2017 at 16:29
  • I removed the links. Later, I would improve the answer (or someone else post a better and updated answer).
    – kokbira
    Aug 1, 2017 at 20:20

Using linux you have a software called trickle that launches a process and limits its bandwidth usage.

  • I'll take a look... but, actually, i'm using kinda 'complicated' system. I run Ubuntu in Win7 (vmware) and use GAE. The reason is - linux command line and no need to install python under windows. But sometimes its getting to much for my laptop (IDE, 2 browsers, bash...and thats all virtualy) so i decided to use my internal IP so i can access the GAE development 'server' from windows. Like 192.168.xxx.xxx:8181/myApp So i, actually, deploy in Windows but it all runs in Ubuntu...So I don't know if trickle can handle with this
    – V-Light
    Jun 14, 2011 at 20:01
  • It's not clear what is virtual on what. If you run Firefox inside Ubuntu inside vmware inside Win7, just call Firefox by trickle -d 10 firefox. If it's the other way around, you may try trickle -d 10 vmware to launch Win7 inside Ubuntu, but I can't say for sure how it will work.
    – user39559
    Jun 16, 2011 at 15:43
  • Win7 is Host (OS which runs virtualization software -vmware workstation 7). Ubuntu 10.10 is a Guest OS. Python and GAE is installed in Ubuntu.
    – V-Light
    Jun 16, 2011 at 19:39
  • So did sudo apt-get install trickle && trickle -d 10 firefox work? You can test it by downloading a big file from a fast server. Make sure firefox is closed when you run this.
    – user39559
    Jun 17, 2011 at 15:23

I would check out Charles Proxy. It has bandwidth throttling and is cross-platform with a very clean interface.


This is free and simple for Mac OS X and works with the every browser: speedlimit


You can use a "slow Internet connection" from a mobile phone (for example, GPRS). You must have a mobile phone that become a modem when connected to the PC and a carrier that provides that kind of connection.

For example, I can connect my LG phone in my computer and use a dial-up program (provided by LG) to perform a connection in TIM, my carrier. So, my internet connection is about 40kbps.

You will have a slow connection, but you cannot adjust its speed only with that.

  • 1
    Although a good idea, it doesn't really answer the question on how to simulate a slow connection. In fact, it is a slow connection.
    – MEMark
    Dec 8, 2014 at 18:50
  • I agree. "To use a simulated slow solution" is different than "to use a real slow solution", because on the first case you probably would have more control on connection speed. But for that particular case where developer is using a computer that can use different internet connection types (wi-fi, rj45...) with different speeds, it is easier to simply change the connection in use than searching and installing particular solutions. Well, it is an alternative.
    – kokbira
    Dec 9, 2014 at 14:05
  • It answers the question on an alternative way - like a HW+procedure way where it is expected a SW+programming way.
    – kokbira
    Dec 9, 2014 at 14:06

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