Tiny Tools › URL parameter glossary › mibextid
mibextidA share/session identifier Facebook's mobile app tacks onto almost every outbound link you tap or copy from it. The value (something like mibextid=abc123) ties the share back to the app session that produced it, so Meta can see how a link travelled. It's the reason links pasted out of the Facebook or Messenger app look so long. Pure tracking — the destination page loads identically without it.
Safe to remove? Yes. mibextid is used for tracking and reporting only — deleting it does not change the page you land on. Strip it before sharing a link to keep it clean and private.