If you've ever tried to look up someone's address online, you've probably discovered that most people search directories will only dish up the details if you take out a subscription. If you don't want to fork out the dough, your options are more limited. That said, there are still plenty of resources that can help you find an up-to-date address – 100 percent cost-free.

Whitepages.com is the leading source of contact information in the United States. If a person is listed in the phone directory, you'll likely find him here. It's completely free to run a basic search; just type the person's name into the search field, and see what turns up. You can narrow the search by state or city, or skip this field to search nationwide. A free search will generally give you instant access to a current address and landline telephone number.

Another popular option is Zabasearch.com. This website is free for a basic search and does much the same job as Whitepages, but it claims to search more public records. So if you can't find the address you're looking for in the phone directory, then it's worth spending a couple of minutes here. Tracing someone is quick and easy; you just need to enter the person's name and location into the search bar. Zabasearch makes money by offering premium search services. However, you can generally find an up-to-date address, phone number and even a date of birth through its cost-free, registration-free service.

Pipl is a unique tool in that it searches the "invisible web," or the millions of web pages that are generally inaccessible to conventional search engines like Bing or Google. Good examples are databases and web pages that are hidden behind a registration barrier. You can search Pipl in various ways: by name, phone number, email address or username. You can also specify a location to focus results. Pipl is completely free at the point of use, and you don't have to register an email address. Search results usually include the person's street address and previous addresses, telephone number and a list of associated people such as family members.

FamilyTreeNow.com is marketed as a genealogy website, but it's not just for building your family tree. The free information you can find on this site includes past and current addresses, phone number, email addresses, date of birth and a substantial list of possible family members or associated persons. The site pulls information from public records, and it's completely free to use. All you have to do is type in a name, with optional additional search fields to narrow results.