What tools are commonly used to measure webpage performance and what are their pros/cons?

http://www.Dotcom-Monitor.com BrowserView product...full disclosure I work at Dotcom-Monitor. It provides an external check using Chrome, IE, or Firefox browsers that measures network time and page element render time. Its used to measure webpage performance from a user's perspective and based on those measures to make page element adjustments (including addressing third-party host issues and network issues)  to reach webpage load-time goals.

I have used http://tools.pingdom.com/ to get the page Load Time. Use that as the starting point and see whats taking up the most amount of time. I also use YSlow plugin for firefox, gives you a good insight. Finally, I used http://loadimpact.com/ to test the site for Load - upto 50 users is free. Thanks, Vishal http://www.iamvalue.com/

http://www.yottaa.com is free and provides various performance metrics including global reachability, time to first byte, time to interactivity, etc.

Great Answers. I did not know about a couple of tools listed above. Thank you for posting them here. I have personally used AOL PageTest for IE (it's a free tool). Chrome & Safari have their own Developer Tools which can help you find out components which are heavy OR taking maximum time to load.

Appdynamics provides a complete system monitoring with very little overhead, you can try a lite version to see the depth of information you can get. The tool provides end user monitoring which you are mainly looking for plus the code level details and traces to track and resolve the issues when then occur.

Many users on IT Central Station use application performance management tools to measure webpage performance. You can read real user reviews for all the major https://www.itcentralstation.com/categories/application-performance-management?tid=thread-quora on the IT Central Station website. New Relic APM is currently ranked the #1 APM tool by our users.  This user writes that while some of the third party plugins can be improved, "New Relic has changed the way we are dealing with application problems. It's the first place for our administrators to check if we encounter issues." For the full review: https://www.itcentralstation.com/product_reviews/new-relic-apm-review-31513-by-guido-schade?tid=thread-quora

New Relic RPM has a free product for monitoring website performance. I work there, so take what I say with a grain of salt, but I don't think there is anything like New Relic. The founder of New Relic is the founder of Wily, so the company has a long history in this realm.

Monitor Scout (https://www.monitorscout.com) provides free website and server monitoring services in beta. And I really don't see any disadvantages if you would sign up with any such services. They offer you many benefits. There are various other tools available in the market to monitor your web page performance, downtime etc. but I trust Monitor Scout the most as they don’t use any untrusted software in your server, rather they use well known Internet protocol SNMP in order to monitor your server health, which will give all the information about your website and server in details from CPU usage to processes, file system, memory any many more.

I use Apache JMeter for Web and Database performance testing. We have created a library about JMeter, and we constantly add materials to it, http://blazemeter.com/blog