I see lots of questions about who uses OpenVMS. In general, places where downtime and security breaches are frowned upon, as well as markets where VMS has had a long-time presence, and where moving away doesn't solve any problems they have and just costs money (in some industries, particularly the cost of re-certifying systems).

Without giving away any specific customers, I have personally dealt with VMS customers in the following markets: nuclear industry (power plants, research reactors, reprocessing plants, research labs), military (weapons systems, logistics), law enforcement, railroads, airports, healthcare, manufacturing (process control, logistics), retail, and I may have overlooked some markets.