What is an Instagram user ID?
Every Instagram account has a numeric user ID, for example 427553890 for @leomessi. Instagram gives it once, when the account is created, and it never changes. The username is only a label on top of it: people can rename their account, but the ID stays the same.
What you need it for
Developer tools and the Instagram Graph API work with IDs instead of usernames. Ad platforms, analytics tools and giveaway pickers often ask for it too. Because the ID does not change, it is also the safest way to keep track of an account in a spreadsheet or a script when the username might change.
How this finder works
Type the username and the page asks our server for the public profile, the same data the live follower counter uses. Only public information is shown: the ID, the name, the picture and the follower count. Private accounts work too, because their ID and follower count are public.
Follower and like counts
Want the follower count as well? The Instagram live follower count shows it to the last follower, and the Instagram like counter follows the likes of a single post live.