Broken on purpose. Rated 1 out of 5 stars

To force users to switch from Firefox to Chrome. Seek for alternatives.

Problem Rated 1 out of 5 stars

I just install it but not working correctly . What can i do for this ?????????

Broke Rated 1 out of 5 stars

Broke on latest version

Rated 5 out of 5 stars

this is best but, i am not able to work, please help

Not working Rated 1 out of 5 stars

It dosen't working.

YSlow no longer working Firefox 40.0.3 Rated 1 out of 5 stars

Buttons cannot be clicked. None of them, as far as I can tell. Tried several times just to make sure I wasn't crazy, but yeah, this appears to be bricked.

Rated 1 out of 5 stars

Does nothing in Firefox 40.x. Run Test button does nothing. All other tabs also not working. Please fix this.

Run Test broke Rated 1 out of 5 stars

Run Test does nothing. Wasted space on the add-on pages. Remove this garbage.

YSlow does not work anymore with the latest version of Firefox (V39 FF) Rated 4 out of 5 stars

YSlow does not work anymore with the latest version of Firefox (V39 FF)

YSlow links disabled Rated 4 out of 5 stars

YSlow is a decent app, but there is a need to develop it, which the founder is doing, but slowly as he/she has not worked with FF recently. It is possible to get a grading and look at the header of each component, including HTTP requests, Use a CND, avoid empty src or href, ... , make favicon small and cachable. This is done as a workaround as follows:

1. Go to Add-ons (about:addons)
2. Click on Options button of YSlow
3. Select Automatically run YSlow when page finishes loading

So the important question is: why slow at developing YSlow?

Rated 1 out of 5 stars

Yslow not working !!!

Rated 5 out of 5 stars

Kudos to Barbequemeister for the workaround.
As others have noted, YSlow has not been updated in some time to work with the newest FF releases.
However, if you *only* want to use YSlow and are willing to forego the latest FF updates, BBQmeister found an "older" but supported version of FF that still supports YSlow. The ESR version is the "Enterprise" version of Firefox that is deliberately configured several generations behind the standard version - this is to ensure stability for enterprise users. For now, at least, the ESR is "old" enough such that YSlow still works.
It is June 2015 and I just installed the ESR 31.7.0 version for Windows. I have Firebug 2.0.11 and YSlow Seems to work fine.
NOTE: Barbecuemeister's admonition in installing the ESR version - unless you rename your current Firefox, the ESR version will overwrite your current Firefox. You can have both installed simultaneously.

Rated 1 out of 5 stars

This tool has not worked in months. What a shame, because if it was working, I would give it a 5 and recommend it to all web developers.

Got broken Rated 1 out of 5 stars

Used to be five stars, now its one. It's been broken since Firefox 36, no updates from the developer. So sadness.

YSlow Not working Rated 3 out of 5 stars

I am using Firefox 38.0.1 .... :( Yslow not working !!!

How to get it work Rated 5 out of 5 stars

Use the latest Firefox ESR Version. I used Firefox ESR 31.6.0 for Mac OSX.
Install the Firebug 1.12.8 Addon.
Install the YSlow 3.1.8 Addon.
Open the Firebug Extension and from there you can use YSlow.
Works perfect.

PS: Ich you will have 2 different Firefox versions on the Mac, just rename the Firefox program to "Firefox 37" or a similar name. Than you can install the ESR Version and rename it to Firefox ESR. After that you can rename "Firefox 37" back to Firefox or whatever you want. Both Firefox programs will share bookmarks and so on. YSlow will only work with the Firefox ESR version.

Stopped working on later versions Rated 1 out of 5 stars

such a great addon cannot have been ignored for so long now by the devs (it's been almost a year since it stopped working properly) - most importantly, rulesets, help, and most important of all... printable view don't work. please fix this otherwise brilliant addon.
one star until it's working again, unfortunately, otherwise i'd give it five.

Call for help

Since most of you missing YSlow on FF are very likely to be a developer who cares about YSlow + Firefox + Firebug. I kindly call for your help. It's been years since I'm not following FF nor FB development. Chances are some change on their end broke YSlow. If only one of you could spend some time investigating I'd be more than happy to merge a PR on Github and push to Mozilla. Thanks.

Rated 1 out of 5 stars

This does not work on Firefox at the moment. None of the buttons are clickable.

Not working on Firefox 37.0.1 Rated 1 out of 5 stars

Does not work on Firefox 37.0.1

Please fix...


The best addon, but why it doesn't work? Rated 5 out of 5 stars

It is much more better then google's page speed on chrome, so please improve it's work with latest firefox!

Will take a look tonight.

Although I'm swamped, I'll try to take a look tonight. It might take some time since it's been a while I'm not developing for Firefox.