diff --git a/keyserver/src/fetchers/community-fetchers.js b/keyserver/src/fetchers/community-fetchers.js
--- a/keyserver/src/fetchers/community-fetchers.js
+++ b/keyserver/src/fetchers/community-fetchers.js
@@ -37,4 +37,18 @@
   return communityInfos;
 }
 
-export { fetchCommunityInfos };
+async function checkIfFarcasterChannelTagIsValid(
+  farcasterChannelID: string,
+): Promise<boolean> {
+  const query = SQL`
+    SELECT id
+    FROM communities
+    WHERE farcaster_channel_id = ${farcasterChannelID}
+  `;
+
+  const [result] = await dbQuery(query);
+
+  return result.length === 1;
+}
+
+export { fetchCommunityInfos, checkIfFarcasterChannelTagIsValid };
diff --git a/keyserver/src/responders/thread-responders.js b/keyserver/src/responders/thread-responders.js
--- a/keyserver/src/responders/thread-responders.js
+++ b/keyserver/src/responders/thread-responders.js
@@ -179,6 +179,7 @@
     threadID: tID,
     calendarQuery: t.maybe(entryQueryInputValidator),
     inviteLinkSecret: t.maybe(t.String),
+    farcasterChannelID: t.maybe(t.String),
   });
 
 async function threadJoinResponder(
diff --git a/keyserver/src/updaters/thread-updaters.js b/keyserver/src/updaters/thread-updaters.js
--- a/keyserver/src/updaters/thread-updaters.js
+++ b/keyserver/src/updaters/thread-updaters.js
@@ -45,6 +45,7 @@
 import createMessages from '../creators/message-creator.js';
 import { createUpdates } from '../creators/update-creator.js';
 import { dbQuery, SQL } from '../database/database.js';
+import { checkIfFarcasterChannelTagIsValid } from '../fetchers/community-fetchers.js';
 import { checkIfInviteLinkIsValid } from '../fetchers/link-fetchers.js';
 import { fetchMessageInfoByID } from '../fetchers/message-fetchers.js';
 import {
@@ -816,17 +817,28 @@
     throw new ServerError('not_logged_in');
   }
 
-  const permissionCheck = request.inviteLinkSecret
-    ? checkIfInviteLinkIsValid(request.inviteLinkSecret, request.threadID)
-    : checkThreadPermission(
-        viewer,
-        request.threadID,
-        threadPermissions.JOIN_THREAD,
-      );
+  let permissionCheckPromise = checkThreadPermission(
+    viewer,
+    request.threadID,
+    threadPermissions.JOIN_THREAD,
+  );
+
+  if (request.inviteLinkSecret) {
+    permissionCheckPromise = checkIfInviteLinkIsValid(
+      request.inviteLinkSecret,
+      request.threadID,
+    );
+  } else if (request.farcasterChannelID) {
+    permissionCheckPromise = checkIfFarcasterChannelTagIsValid(
+      request.farcasterChannelID,
+    );
+  }
+
   const [isMember, hasPermission] = await Promise.all([
     fetchViewerIsMember(viewer, request.threadID),
-    permissionCheck,
+    permissionCheckPromise,
   ]);
+
   if (!hasPermission) {
     throw new ServerError('invalid_parameters');
   }
diff --git a/lib/types/thread-types.js b/lib/types/thread-types.js
--- a/lib/types/thread-types.js
+++ b/lib/types/thread-types.js
@@ -302,11 +302,13 @@
   +threadID: string,
   +calendarQuery?: ?CalendarQuery,
   +inviteLinkSecret?: string,
+  +farcasterChannelID?: string,
 };
 export type ClientThreadJoinRequest = {
   +threadID: string,
   +calendarQuery: CalendarQuery,
   +inviteLinkSecret?: string,
+  +farcasterChannelID?: string,
 };
 export type ThreadJoinResult = {
   +updatesResult: {