ThisNumber is described as 'International directory of white pages, yellow pages, and online phone books'. There are four alternatives to ThisNumber, not only websites but also apps for . The best alternative is Pipl. It's not free, so if you're looking for a free alternative, you could try Spokeo or Reported Calls.
Pipl is the easy way for businesses to get contact, work & social information about people. The most comprehensive people search on the web. Pipl finds high-quality results in pages that cannot be found on regular search engines.