BuiltWith is a nifty Chrome extension that has a great freemium offering. You can pay to get detailed analytics on every site's building blocks including start and end dates for each plugin being used. For someone in tech sales, it helps me identify if prospects currently use our vendors, if they use a competitor, or if they don't have any system in place at all.

The chrome extension of the tool is super cool. With just one click you get all the technologies a website has and it helps me prepare well for my call with the customer. By just looking at the data I am in a much better position to give the custom integration solution to my customer.

Since I do a ton of prospecting, Builtwith helps me open up conversations and identify worth while accounts of targeting. A lot of the time, tech stacks are hidden which makes it really hard to reach out to companies who might have an actual need for Datadog.