If you are are bothering how much traffic your competitor’s website is getting daily, you can use very easy and user friendly Statbrain.com. At this website you can get estimated number of visits per day for any website. You just need to supply URL of website.
I checked for my blog traffic, i found that result given by Statbrain is almost correct. For curiosity I checked Number of daily visits of google.com, the result for google.com is 52,097,973 visits per day. Yahoo.com daily visitors count is 111,616,149 visits per day according to statbrain.
So, how it works? According to statbrain-
Statbrain contains a collection of actual number of visits from hundreds of websites. The visitor data is combined with information about number of links that point towards the site, country, Alexa ranking and other data that is available on-line.
They have developed complex mathematical formula to reach near to actual value of traffic of any website.
This is a good tool for those who want to research for traffic before starting any website.