1. Google Developers : With PageSpeed Insights you can identify ways to make your site faster and more mobile-friendly.
2. WEBPAGETEST : WebPagetest is an open source project that is primarily being developed and supported by Google as part of our efforts to make the web faster.
WebPagetest is a tool that was originally developed by AOL for use internally and was open-sourced in 2008 under a BSD license. The platform is under active development on GitHub and is also packaged up periodically and available for download if you would like to run your own instance.
3. GTMetrix : GTmetrix can help you develop a faster, more efficient, and all-around improved website experience for your users.
Your users will love you for it.
4.Pingdom : This tools built this Website Speed Test to help you analyze the load speed of your websites and learn how to make them faster. It lets you identify what about a web page is fast, slow, too big, what best practices you’re not following, and so on. We have tried to make it useful both to experts and novices alike.
5. LoadImpact : This tool easily load test your website or web app. Record user scenarios using our Chrome extension or proxy recorder and configure a test with just a few clicks. Easy-peasy-lemon-squeezy!
URL : http://loadimpact.com/