Hashicorp builds tools that solve tightly focused real-world DevOps problems. Their solutions nearly always match my own mental model of the problems’ shape and extent. The Unix philosophy shines through: Hashicorp’s tools are independent but composable; developers can mix and match to meet their unique needs.
We use a couple Hashicorp tools at Cloak. If we had the bandwidth to improve our process and infrastructure, we’d quickly use a couple more. Vault solves a problem we’ve already had to solve ourselves, but it appears to do so in a much more complete and elegant way.