Reliable Technographic data is hard to find. Plus there are many other considerations that should be taken into account. Builtwith and Datanyze rely on Web Scraping and so are literally dozens of other vendors. If the technology you are looking to target is used in the web layer like intercom or marketo (forms / landing pages) or hubspot ( forms / landing pages) you are likely to find a decent amount of data ( about 30-60% of all available companies depending on the vendor you are using) from vendors like Builtwith and Datanyze. However if the technology you are looking for is used behind-the-firewall do not expect more than 10% coverage from BuiltWith and Datanyze in my experience. These tools do differ however in their ability to mesh that information with company or role level information. Say you want to find “find VP of marketing contacts from companies with employee size 200-1000 who use Marketo” , you need your data provider to take into account technographic information which in this case is Marketo but also find you the email address / phone number for VP of marketing along with making sure the company is 200-1000 employee category. As you look for the vendors you should take all of this into consideration.
In terms of getting Technographic data HG Data is one of the best sources of reliable data (because they use other means other than scraping to get the behind-the-firewall data), but they are pretty expensive. You are better off looking for other vendors who resell HG Data.
These tools largely look for traces of software used to build public web pages (mostly websites). So depending on what you are looking for it may work. It doesn't for most B2B software vendors.