UDID.tech uses Apple Mobile Device Management concepts to provide you information about your device. The profile you install tells your iPhone, iPad, or iPod to send encrypted data (UDID, IMEI, Serial No, etc.) to your browser. This profile is temporary and exists on your device only for a few moments to send encrypted data. After this, the profile is automatically removed from your iOS device. We do not store or reuse any of your device information.
To check if there are any profiles installed on your device, go to iOS device Settings->General->Profiles. If there is no such section, then there are no installed profiles on your device.
You can use your UDID to allow iOS-developers to make apps for you and access beta versions of iOS.
UDID is short for Unique Device Identifier. It is a 40-character long value containing alpha-numeric symbols (a-z and 0-9). It is a unique identifier for a single device fetched from Apple servers when a user tries to activate the device using iCloud or the Setup app.
Developers use the UDID to register devices for testing their apps. One can run apps that are not in Apple's AppStore yet only on the registered devices. Developers currently have up to 100 UDIDs they can register.
Note that the UDID of your device may alter after changes to the device, for example, after repair, because on some models, UDID is generated particularly from MAC addresses of network interfaces your device has.
iPhone or iPad Serial Number identifies the device model. It is provided by the manufacturer. A serial number of any device may contain party number or any other info related to the device model you're holding in your hands. Some Apple™ support resources ask Serial no. of your device to give you more relevant info or provide you with more accurate support.
IMEI is The International Mobile Station Equipment Identity /aɪˈmiː/. It is a unique identifier across all mobile phones, as well as some satellite phones too. GSM networks use the IMEI number to identify valid devices and stop a stolen phone from accessing the network.
The IMEI number also reveals loads of other details about a phone. These include the brand and model, year of release, and specifications.
Please, avoid sharing IMEI and UDID with third parties you don't trust because you may facilitate the work of thefts and fraudsters. Anyway, if anything fraudulent happens, contact Apple™ support and police and be guided by the country's laws where the incident occurred.