miji.beA URL preview is a feature that lets you check the destination URL and a summary of the page before you actually open a link. It is especially useful for links whose destination is not obvious at a glance, such as short URLs. By taking in the expanded address and the page title before clicking, you get a clue for avoiding accidental visits to phishing scams or malware distribution sites.
The information a URL preview shows typically includes the full destination URL after any redirects, the page title, the meta description, the OGP image, and an assessment of the domain's safety. Comparing these lets you confirm, before opening the link, whether the wording of the link matches where it actually leads.
A URL preview is easily confused with link expansion (URL expansion). Link expansion restores a short URL to its original long URL and shows only the final destination, whereas a URL preview presents the destination address together with additional clues such as the page title, a summary, and an image. The richer preview makes it easier to judge whether the destination is a legitimate service.
There are mainly two ways to implement URL previews. One adds a + to the end of a short URL to display a preview page (used by Bitly), and the other provides a dedicated preview page URL. In either approach, the preview page itself must use HTTPS and appropriate security headers so that it cannot be disguised as a phishing site.
When you look at a preview, the points worth checking are whether the displayed domain matches the service you expect, whether it is protected by HTTPS, and whether the page content fits the context of the link. Misleading domains that imitate a legitimate brand by changing just a single letter of the spelling are easy to overlook unless you compare the address carefully. In addition, dynamic short URLs can sometimes have their destination swapped later, so where a link leads may differ between the moment of preview and the moment you actually open it.
When you receive a short URL, the basic steps are to check the destination with a preview, compare whether the domain is the legitimate one, confirm that it is protected by HTTPS, and refrain from opening the link if anything feels suspicious. It helps to keep in mind that a preview is only one piece of information for making a judgment, and it does not by itself guarantee safety.