[krautsourced]

Sociomantic is using it for their systems, https://www.sociomantic.com/jobs/d-software-developer/

[_ak]

Last time I seen one of their ads, they emphasized that their code base is still D1. I don't know whether that changed since then.

[FraaJad]

they have since moved to D2. One of their developers gave a talk about the Big Migration in D conf.

edit: They have series of blog posts documenting the same too - https://www.sociomantic.com/search/tag/dlang (6 so far).