Keep in mind that there are many people finding tools available out there. The websites referenced in this LibGuide represent just a small portion of those. Also, each website listed will have its strengths as well as some weaknesses. Some people will be found easily on some and some may not be found on others.
Also keep in mind that many of these sites will only provide minimal information for free. Details on that person may require purchasing a subscription to that resource.
Don't underestimate the power of searching social media. You will be surprised, or maybe not surprised, by the type of content people will make available online. Searching for known aquaintances may also lead to information on the person you are looking for.
Whitepages has sections on finding people, locating businesses, performing a reverse phone lookup, and a feature called "Address and Neighbors" which allows you to find out the names of everyone residing in a particular area.
Pipl claims to search the "deep web" in search of more relevant results on people. Most of the results retrieved are from other search databases that charge a fee, but it can still be a good start. Requires paid account.
Searchbug has a few free links for finding people and performing reverse phone lookups.
Instant Check Mate looks specifically for known associates, aliases and criminal background information. Full reports are available for a fee. This is a good resource for identifying aliases and other known relatives or associates. See instantcheckmate.com/reviews for reviews of the product. Requires Paid Account.
Anywho, from AT&T, provides White Pages information, Yellow Pages information, reverse phone lookup, and area and zip code lookup.
Spokeo is another people finding tool that only provides minimal free information, with links to paid content.
ZabaSearch is another search engine with people searching capabilities. There is also a feature that allows you to see if anyone has sent you a message, in the fourth tab on the top!
Facesaerch allows you to type in someone's name and find that person's image (from Facebook, Twitter, etc.) with links to that person's social media account.
Peoplefinders is another tool for tracking down people. Like many of these sites, though, detailed information requires signing up for an account and paying a fee.