Tiny Tools › URL parameter glossary › utm_source
utm_sourceNames where a visit came from — e.g. newsletter, twitter, google. Part of the UTM family that virtually every marketing team adds to shared links so their analytics can attribute traffic to a channel.
Safe to remove? Yes. utm_source 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.