There are several resources that include data from Similarweb, an aggregator of website traffic information:

• PitchBook includes unique visitors to a company's website over the most recent three-month period in the Signals section on a company's record.
• Bloomberg (see access details) also makes Similarweb information available for companies via the ALTD (Alternative Data) function.
• Dewey has a longer time series of Similarweb website traffic visits data (desktop and mobile visits). Other Similarweb series on Dewey include Daily App Engagement and Desktop Search Keywords.