We use it at our company for our inventory system. We make hundreds of concurrent http requests per minute and parse json and soap responses that are up to 8 MB in size. We're a tiny team, so while its possible to accomplish this in many tech stacks, functional programming, pattern matching, immutable variables and other Elixir/Erlang features make it easy to release a stable product quickly. This project has been in production for 2.5 years and has been working beautifully.