etcd is used as the primary data store of applications like Kubernetes or CoreDNS. But, many use it for configuration like M3 or Vitess. You can see different users in the docs[1].
There are different databases like CockroachDB or Dgraph that use etcd's raft libraries but build more application focused (SQL, graphql, etc) APIs[2].
There are different databases like CockroachDB or Dgraph that use etcd's raft libraries but build more application focused (SQL, graphql, etc) APIs[2].
[1]: https://github.com/etcd-io/etcd/blob/master/Documentation/in...
[2]: https://github.com/etcd-io/etcd/tree/master/raft#notable-use...