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InfoQ Homepage News Yahoo! Has Open Sourced YSlow

Yahoo! Has Open Sourced YSlow

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Yahoo! has decided to open source YSlow. Developers no longer need to submit feature requests to Yahoo!, being able to improve the tool themselves. Comparing YSlow with Google Page Speed.

After many years of making it freely available under Mozilla Public License MPL 1.1, Yahoo! has decided to open source YSlow under a BSD license. The Yahoo! Exceptional Performance group used to gather feedback from the community in order to improve the tool. Developers can now do whatever they want with the tool. Marcel Duran, a Yahoo! Frontend Engineer who’s been in charge of the project, has made the YSlow code available on GitHub, inviting developers to fork the code and make pull requests that will later will be merged back into the development repository if accepted. Duran will also update the add-ons across all supported browsers. From now on, the community will no longer depend on Yahoo! to implement certain feature requests.

YSlow is a web page performance tool similar to Google’s Page Speed which was open sourced back in 2009 under an Apache 2.0 license. There are some differences between the tools. While YSlow has add-ons for Firefox, Chrome, Safari, Opera, including the mobile versions via a bookmarklet, and also can be executed at the command prompt, Page Speed has extensions only for Chrome and Firefox. But Page Speed comes with a service for analyzing web pages, including those targeted at mobile devices. Page Speed also has an Apache module for optimizing pages by rewriting various page resources, HTML, JavaScript, CSS, JPG, PNG.

Both tools analyze pages on a set of rules listed below:

 Besides analyzing the pages, the tools suggest changes that are meant to improve the web page loading speed.

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