diff --git a/blahd/docs/webapi.yaml b/blahd/docs/webapi.yaml
index 1064664..e9f1b4e 100644
--- a/blahd/docs/webapi.yaml
+++ b/blahd/docs/webapi.yaml
@@ -24,10 +24,11 @@ paths:
           in: query
           required: true
           description: |
-            Either "public" or "joined".
-            For "public", it returns all public rooms on the server.
-            For "joined", `Authorization` must be provided and it will return
-            rooms user have joined.
+            Must be one of following values:
+            - "public": list all public rooms on the server.
+            - "joined": list rooms the user have joined.
+            - "unseen": list rooms the user have joined and have unseen
+              messages.
         top:
           in: query
           description:
@@ -41,7 +42,9 @@ paths:
             should be included (as the same value) for each page fetch.
       headers:
         Authorization:
-          description: Proof of membership for private rooms. Required if `filter=joined`.
+          description: |
+            Proof of membership for private rooms.
+            Required if `filter` is other than "public".
           required: false
           schema:
             $ret: WithSig<AuthPayload>
diff --git a/blahd/src/main.rs b/blahd/src/main.rs
index 7a6da24..23adac9 100644
--- a/blahd/src/main.rs
+++ b/blahd/src/main.rs
@@ -213,8 +213,12 @@ struct ListRoomParams {
 #[derive(Debug, Deserialize)]
 #[serde(rename_all = "snake_case")]
 enum ListRoomFilter {
+    /// List all public rooms.
     Public,
+    /// List joined rooms (authentication required).
     Joined,
+    /// List all joined rooms with unseen messages (authentication required).
+    Unseen,
 }
 
 async fn room_list(
@@ -261,12 +265,14 @@ async fn room_list(
                     .transpose()?;
                 let last_seen_cid =
                     Some(row.get::<_, Id>("last_seen_cid")?).filter(|cid| cid.0 != 0);
+                let unseen_cnt = row.get("unseen_cnt").ok();
                 Ok(RoomMetadata {
                     rid,
                     title,
                     attrs,
                     last_chat,
                     last_seen_cid,
+                    unseen_cnt,
                 })
             })?
             .collect::<Result<Vec<_>, _>>()?;
@@ -320,6 +326,36 @@ async fn room_list(
                 },
             )
         }
+        ListRoomFilter::Unseen => {
+            let user = auth?.0;
+            query(
+                r"
+                SELECT
+                    `rid`, `title`, `attrs`, `last_seen_cid`,
+                    `cid`, `last_author`.`userkey`, `timestamp`, `nonce`, `sig`, `rich_text`,
+                    (SELECT COUNT(*)
+                        FROM `room_item` AS `unseen_item`
+                        WHERE `unseen_item`.`rid` = `room`.`rid` AND
+                            `last_seen_cid` < `unseen_item`.`cid`) AS `unseen_cnt`
+                FROM `user`
+                JOIN `room_member` USING (`uid`)
+                JOIN `room` USING (`rid`)
+                LEFT JOIN `room_item` USING (`rid`)
+                LEFT JOIN `user` AS `last_author` ON (`last_author`.`uid` = `room_item`.`uid`)
+                WHERE `user`.`userkey` = :userkey AND
+                    `rid` > :start_rid AND
+                    `cid` > `last_seen_cid`
+                GROUP BY `rid` HAVING `cid` IS MAX(`cid`)
+                ORDER BY `rid` ASC
+                LIMIT :page_len
+                ",
+                named_params! {
+                    ":start_rid": start_rid,
+                    ":page_len": page_len,
+                    ":userkey": user,
+                },
+            )
+        }
     }
     .map(Json)
 }
@@ -466,8 +502,10 @@ async fn room_get_metadata(
         rid,
         title,
         attrs,
+        // TODO: Should we include these here?
         last_chat: None,
         last_seen_cid: None,
+        unseen_cnt: None,
     }))
 }
 
@@ -579,11 +617,15 @@ pub struct RoomMetadata {
     pub title: String,
     pub attrs: RoomAttrs,
 
-    /// Optional extra information. Only included by the room list response.
+    // Optional extra information. Only included by the room list response.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub last_chat: Option<WithItemId<ChatItem>>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub last_seen_cid: Option<Id>,
+    /// The number of unseen messages. Only available for `room_list` response with
+    /// "filter=unseen".
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub unseen_cnt: Option<u64>,
 }
 
 fn get_room_if_readable<T>(