There are third-party websites (such as swappa.com or imei.info ) that allow serial number lookups.
Beyond authenticity, a serial number check unlocks critical service and support information. For a used iPhone or a hand-me-down MacBook, knowing the exact model, technical specifications, and original purchase date prevents misinformation. More importantly, the tool reveals the remaining eligibility for AppleCare+ coverage and the standard one-year limited warranty. This knowledge is invaluable before buying a second-hand device: a unit with active coverage offers peace of mind, while one that is “out of warranty” may signal impending repair costs. Additionally, the check will flag a device as “Replacement Serial Number” if it was issued after a service repair, providing full transparency. check by serial number apple