I'd be interested to hear what free tools and services people use to gauge levels of traffic and the nature of the audience to any website?
Obviously this information is useful for competitive intelligence, media planning and buying, search optimisiation, online PR, affiliate marketing etc.
Following are the ones we use:
We use this to look at other sites and we've also put the Quantcast tag on our site so you can see data on Econsultancy there. From what we can tell it is reasonably accurate (because of the tag and directly measured traffic) compared to our actual figures and compared to those services which are based on toolbar data (like Alexa).
Most people know of Amazon-owned Alexa which bases its stats on data collected via its toolbar. Econsultancy is listed here too and the quality and accuracy of the information has improved over the years but still isn't as accurate as Quantcast as it is sample-based.
This seems to be gaining increasing traction, particularly in the US. It's got some quite nice interfaces and site-to-site comparison tools. The data accuracy isn't bad and it pulls through some useful other data (e.g. search and referral analytics) though you have to pay for the Pro version to get fuller details. The Econsultancy Compete profile looks a bit odd due to our change of domain at the end of last year but it's becoming more accurate now.
This is a relatively new service from Google (still in their "Labs"). It's useful for trends, and site comparisons, and is quite good for seeing the geographic coverage and reach of a particular site, as well as getting some insight into competing sites through the 'also visited' data. Again, the Econsultancy profile is a bit skewed by our recent domain change but looks like impressive growth!
This is quite a nifty new entrant. There is no proprietary data provided by dataopedia but it does a good job of pulling together data from a wide range of sources. These include all of above, but are further supplemented by measures of popularity by pulling through data from the likes of StumbleUpon, Digg, Delicious, Google News, Twitter etc. There is also company information, domain/technical information, PageRank etc. The Econsultancy.com profile is somewhat skewed by our recent domain name change but is starting to reflect actual figures.
What do you use? What do you find to be most useful, most accurate etc?