Web site performance tools?

YSlow, dynaTrace, HTTPWatch, Fiddler .........

All these things are really good for measuring the performance of the website and get statistics for the same. YSlow is really cool, offers good guidelines also.

However, i am very confused with so many things around (Though it's good that people already invested time and have made nice guidelines to follow and i thank them for great work done).

Following are my questions:

1. How much accuracy these tools have in terms or numbers they show ?
2. Which one(tool) is BEST 开发者_StackOverflow中文版to use (one for all needs)? Or i am missing name of some tool which is out of box and better than above all?

I'm suprised that you haven't mentioned JMeter. It is free, quite easy to use, has lots of features, and great for load testing your website.

As for question one, I'm not sure I can answer that. I'm sure that in general, the numbers these tools show are pretty accurate, but there are some catches. Take JMeter for example:

• JMeter itself uses a lot of memory and also some substantial CPU time if you do some heavy load testing. That means that if you run the tool on the same machine as your website, some resources are lost, e.g. not available for the website
• Testing it on the same machine does not out-of-the-box take in account that the data has to be sent over the internet connection, so response times are lower then the reality.

But in all, I think you should never blindly trust the results these tools give you, but they can give you a good insight into possible bottlenecks or problems.

YSlow is good to measure performance for a single user. Try to keep it grade A and it will be OK. But it actually doesn't measure performance in case of multiple concurrent users. For that you can use under each Apache JMeter. It's a good webserver/webapplication stresstest tool. So I would say, just use both YSlow (for client performance) and JMeter (for server performance).

I haven't used DynaTrace before, so I'll skip that part. The mentioned HTTP request trackers doesn't really measure performance, they are more debuggers.

As far as I am concerned, i find YSlow to be really good (have tried fiddler too) and it does help me when i need it and i do believe that it provides the correct figures thereby making me use that in the time ahead too unless there is anything unanimously accepted (which is difficult because everyone has different choices and requirements.) or even better. Oh they are right, forgot the JMeter, something you should definitely give a mention.

There is also Speed Tracer extension for Chrome. It should be usable with any JavaScript heavy website.

http://code.google.com/webtoolkit/speedtracer/

http://gtmetrix.com is a good tool and it is free. that analyzes your page's speed performance using Page Speed and YSlow