Similarweb API
Similarweb (similarweb.com) has 2 public methods: list top websites and get website traffic. Each costs 1 credit per completed run (1¢ with pay as you go); failed runs are free.
Unofficial. Not affiliated with or endorsed by Similarweb.
Methods
2Lists Similarweb's most visited websites for a category and country, with rankings and engagement figures for the reported month. Anonymous view limits may restrict results, especially for country rankings.
Returns month, rank, domain, category, rank change, visit duration, pages per visit, bounce rate, Similarweb link
Readsimilarweb.com/list_top_websitesGets a website's monthly traffic estimate, rankings, engagement and top countries from Similarweb's free public overview. Traffic-source percentages withheld by the site are null; the site may limit anonymous views.
Returns month, global/country/category rank, monthly visits, change, bounce rate, pages per visit, visit duration, top countries, traffic sources
Readsimilarweb.com/get_website_traffic