Extract mentions

What it's for

From a caption, a thread or a pile of comments it pulls out every username mentioned with an at sign, one per line. It helps whoever runs a page and has to thank or get back to the people who were tagged, whoever is putting together a list of collaborations, and whoever wants to see quickly who is named in a long conversation without scrolling through all of it.

How it finds them

Anything starting with @ and carrying on with letters, digits, underscores and dots is picked up, those being the characters allowed in social usernames. Accented letters are fine. Duplicates are removed, so someone mentioned ten times appears once, but the comparison looks at capitals: @Mario and @mario stay two entries.

Two things to check again

First: inside a text, an email address has an at sign in the middle, so «john@example.com» produces «@example.com». That isn't a recognition failure, it's that the two things are written the same way; if there are emails in the text, those entries are obvious by eye and get thrown away. If addresses are exactly what you want, the page is Extract emails from text.

Second: the dot is allowed because on many networks it's part of the name, so a mention at the end of a sentence can drag the full stop along («@luca.»). It's one character too many, removed in a second, but worth noticing before you paste the list somewhere.

Nearby tools

For hashtags instead of mentions there is Extract hashtags, and for links Extract links from text. If you're writing the post and want to know how much room is left, the count for each platform is done by Social character counter.