Ever since YSlow for Firefox was first released, it has helped millions of developers analyze web pages and suggested ways for them to improve their websites' performance. YSlow ranks in the Top 25 for Best of 2 Billion Firefox Add-ons downloaded so far. We are very proud of where YSlow stands today and we continue to work hard to take it to the next level.
Today's another "Hello World!" moment for YSlow. We are very excited to announce the beta release of YSlow for Chrome. YSlow looks beautiful inside the Chrome browser.
- Here are some of the feature highlights:
- You'll feel at home here. We kept the user experience consistent with YSlow for Firefox.
- Added the ability to detect post onload components, including for pages that prevent itself from being embedded and/or iframed. (experimental)
- Support for 3 main rulesets: Default YSlow V2, Classic V1, and Small Site or Blog as well as the ability to create new ones based on these 3.
- Offenders in CDN rule are now listed as domains only.
- Runs multiple YSlow instances (new windows). This feature is excellent for comparing YSlow results for different pages side-by-side as shown below.

Some caveats: As of today, the current version of Chrome does not provide access to its network panel. As a result, we have relied on Ajax calls to do most of the heavy lifting for us. Hence, some rules might be affected thus, fluctuating the grades a bit if you compare them with the Firefox version.
Special thanks to Marcel Duran, front-end engineering lead for the Exceptional Performance team, who has led all the development efforts for this next-generation YSlow. We would also like to thank Stoyan Stefanov, our YSlow alumnus, for his valuable technical guidance.
If you’re interested in learning some of the “behind-the-scenes” techniques used to build YSlow for Chrome, please join us for a presentation introducing next-gen YSlow on March 15th during the Velocity online conference.
Last but not least, since this is a beta release, so please voice your feedback, report bugs, or request features on the Yahoo! Group for Exceptional Performance.

15 Comments
That's great. Now please make the tools tab available? I love the smush them all functionality.
Why does the Chrome extension need access to my browser history?
can not work in chrome10 on XP
Absolutely fantastic. One of the reasons I have not fully switched to chrome was because of certain extensions I rely on in Firefox to work effectively and efficiently. This is certainly going to help.
That's awesome!!! More browsers is great! Can't wait to figure out how to run headless Chrome ;)
BTW, how do you configure YSlow in Chrome (e.g. point it at a beacon is my personal interest).
@aaronpeters no idea why chrome is warning about that since yslow manifest.json is not even requesting permission to history (check yslow manifest.json in your extension directory), however yslow does need permission to open a new window and get the selected tab hence according to http://www.google.com/support/chrome/bin/answer.py?answer=95589 it allows opening the history page in a new tab which is not intentioned nor used within yslow code.
@Sergey this is still an early beta version and some features aren't available yet, like tools and firing beacons as well as new under development features, however they will be available anytime soon and we're announcing publicly.
Nice.
HINT: If YSlow fails to run inside Chrome (stable) try restarting Chrome and see if that helps. For Chrome (nightly) a machine restart might be required.
It's still in BETA :) so hang on while we iron out a few issues.
for the same website, yslow gives different results on Google Chrome and Firefox. Does anybody face similar issues?
Its cool. i would to try it to get optmizing. I hope its can made easier to get figured out my Web.
Is there a way to add own cdn hostnames like you do in about:config in Firefox?
@Nilanjana There was some know issues we found and fixed for some rules, we're pushing the fixed version soon, but do expect some slight difference between FF and C because a) some servers serve different content based on user agent b) Chrome has some limitation (due to X-domain AJAX) with some minor rules like redirects which are resolved thus no info available
@s_pettersson We're currently working on this task: Options page for Chrome extension, we'll push this feature as soon as we finish our internal tests
The latest YSlow for Chrome release (3.0.2) has the fix for the popup window issue. Now those who found problems to run YSlow should be able to open the extension normally. Chrome will update it automatically but you can also do it manually.
Thanks!
Is there any web analyser for IE8?