It means the platform's public surface shows no account under that name right now. That is the strongest signal available from outside, but it is not a reservation: a handle can be held by a deactivated, suspended or private account the public page hides, and some platforms reserve names they never show. Click through and register it while you are looking at it, because a free handle is only free until someone else has the same idea.

Because the check could not be completed, and an unfinished check must never be reported as a free name. Platforms rate-limit and block automated lookups, and a few of them, Facebook being the standing example, hide private profiles exactly as thoroughly as free handles, so their answer proves nothing either way. It is also what you see when a platform's own username rules do not accept the string at all: each platform has its own rules on length and on whether dots, underscores or hyphens may appear, so a name with an underscore is fine on Instagram and cannot exist on GitHub. Hover the card to see which of these it was. Every unknown card links straight to the platform so you can check by hand in one click.

Yes. One lookup checks the exact handle you typed, lowercased, because the checked platforms treat handles case-insensitively, so Acme and acme are the same name. Variants with dots, underscores or suffixes are different handles, and worth checking separately if the plain one is taken.

Neither store has a handle to check, so those two answer the question that does apply: how many apps are already called the name you typed. The number counts listings whose own name carries the word, and hovering it splits that into the apps actually called it and the ones using it inside a longer title — on the App Store, “notion” matches twenty-four apps but only five are called Notion, the rest being companion apps like “Widget for Notion”. It is a count of the store's own search results, not a census, so treat it as a floor: zero means the name is clear on the shelf, and a high number means an app under that name will never be found by searching for it.

Only in that a name worth having is worth having everywhere. The domain search checks the same name against every domain extension, and a name that is free as a .com and free on the big platforms is a rarer and better find than either alone. The search page shows a compact version of this check next to every single-name result for exactly that reason.