N-number aviation registration searches are available online at FAA.gov, Landings.com, Aero-Web.org and Avitop.com, as of 2015. AAHS-online.org provides additional information regarding N-numbers and aviation registration.
The Federal Aviation Administration website allows users to search a database of N-numbers that updates each federal working day at midnight. The website also allows users to request and renew N-numbers online.
Landings.com allows users to do a basic N-number search and provides links to additional search options, including an expanded registration search, a serial number search and an owner search. The American Aviation Historical Society features an article about the purpose and history of N-number aviation registration in the United States.