TeamViewer

Released in 2005 by the identically named company in Göppingen, Germany. The pitch was that a support technician could take over a remote machine through firewalls and NAT without the customer touching a single port setting — the connection dials outward to TeamViewer's servers, so both parties can sit behind their own router. Free for personal use, expensive for businesses, which was the business model for years.

It went public in Frankfurt in 2019 in one of the year's biggest German tech listings. The tool has a dark side: scammers routinely use it to coax remote access out of older users ("Microsoft is calling about your virus"), and the company has had to build in warnings against exactly that. Rival AnyDesk and the older VNC protocol do essentially the same job.