There is SimCorp and Issuu that I know of, but I've also been at a meetup hosted by a company doing ReasonML. And there are a couple of people doing OCaml at Ze

There is SimCorp and Issuu that I know of, but I've also been at a meetup hosted by a company doing ReasonML. And there are a couple of people doing OCaml at Zendesk, but I don't know if they use it in production or just for fun.