diff --git a/src/r0/server.rs b/src/r0/server.rs
index bf4489c4..3abcd4cc 100644
--- a/src/r0/server.rs
+++ b/src/r0/server.rs
@@ -1 +1,75 @@
 //! Endpoints for server administration.
+
+/// [GET /_matrix/client/r0/admin/whois/{userId}](https://matrix.org/docs/spec/client_server/r0.2.0.html#get-matrix-client-r0-admin-whois-userid)
+pub mod get_user_info {
+    use ruma_identifiers::UserId;
+
+    use std::collections::HashMap;
+
+    /// Information about a connection in a user session.
+    #[derive(Clone, Debug, Deserialize, Serialize)]
+    pub struct ConnectionInfo {
+        /// Most recently seen IP address of the session.
+        pub ip: String,
+        /// Unix timestamp that the session was last active.
+        pub last_seen: u64,
+        /// User agent string last seen in the session.
+        pub user_agent: String,
+    }
+
+    /// Information about a user's device.
+    #[derive(Clone, Debug, Deserialize, Serialize)]
+    pub struct DeviceInfo {
+        /// A list of user sessions on this device.
+        pub sessions: Vec<SessionInfo>,
+    }
+
+    /// Details about this API endpoint.
+    #[derive(Clone, Copy, Debug)]
+    pub struct Endpoint;
+
+    /// This API endpoint's path parameters.
+    #[derive(Clone, Debug)]
+    pub struct PathParams {
+        /// The user to look up.
+        pub user_id: UserId,
+    }
+
+    /// This API endpoint's response.
+    #[derive(Clone, Debug, Deserialize, Serialize)]
+    pub struct Response {
+        /// The Matrix user ID of the user.
+        pub user_id: UserId,
+        /// A map of the user's device identifiers to information about that device.
+        pub devices: HashMap<String, DeviceInfo>,
+    }
+
+    /// Information about a user session.
+    #[derive(Clone, Debug, Deserialize, Serialize)]
+    pub struct SessionInfo {
+        /// A list of connections in this session.
+        pub connections: Vec<ConnectionInfo>,
+    }
+
+    impl ::Endpoint for Endpoint {
+        type BodyParams = ();
+        type PathParams = PathParams;
+        type QueryParams = ();
+        type Response = Response;
+
+        fn method() -> ::Method {
+            ::Method::Get
+        }
+
+        fn request_path(params: Self::PathParams) -> String {
+            format!(
+                "/_matrix/client/r0/admin/whois/{}",
+                params.user_id
+            )
+        }
+
+        fn router_path() -> String {
+            "/_matrix/client/r0/admin/whois/:user_id".to_string()
+        }
+    }
+}