Tools I like to keep in my toolbag

Over time I have been putting together a list of tools (mostly freebies) that I use as part of Performance Testing and website performance analysis.

Some I use daily , others once per project.


Built by Yahoo and available as an add-on to Firebug for Firefox or as an extension in Chrome.

Gives pages on websites a score – using key metrics – for example whether compression is in use, or whether JS is at top or bottom, cache policies etc

The rules can be tailored – If CDN is not on the radar – take this out of the mix

It also shows component size and time and very usefully  shows cold versus primed cache requests

It gives a raw timing of page load time – this could be on every testers browser then it should be useful even on SIT environments to see if pages > 4 seconds etc….


Needed if you are using Firefox and want YSlow – but is great anyway.

Shows the waterfall of the page loading – shows how the page elements drop in and which ones hold up others.

Allows you to see header and request details – highlight elements

Tamper Data

Good security add-on for Firefox – allows you to intercept the request after page validation and before submitting to server – excellent for seeing if userids etc are sent plain – and allows users to tamper with the data (hence the name)

If, for example, you intercept a call with a login id , what happens if you increase the value by 1 – do you see your own data, error or other persons details.

HTTPWatch (free or paid)

Much like firebug it shows the waterfall of the page elements – free version allows saving and printing (paid version shows more detail of each call)


You can host your own instance ( needs apache and php ) – this allows you to get waterfall and timings either on demand or regularly (use of WPT monitor)

It’s an end game solution – at a former client we had this monitoring the production site, staging and the UI development boxes to see page size and time changes over a longer period of time.

Xenu Link Sleuth

A fantastic freebie tool for crawling a website to find broken links.

Also I use this for building up lists of URLs for doing site wide tests.


Another tool for seeing what is being sent around – like tamper data

it has some cool add ons like Stress Stimulus which allows some very basic load testing to be done


lots of options here – the web edition for measuring the response of AJAX

If you’ve got the cash the server version is excellent and will cut down your problem diagnosis time.