diff --git a/api/user/followed-arms.ts b/api/user/followed-arms.ts
new file mode 100644
index 00000000..fce27197
--- /dev/null
+++ b/api/user/followed-arms.ts
@@ -0,0 +1,102 @@
+export const config = {
+  runtime: "nodejs",
+};
+
+import { createClient } from "@supabase/supabase-js";
+
+const supabaseUrl = process.env.VITE_SUPABASE_URL;
+const supabaseServiceRole = process.env.SUPABASE_SERVICE_ROLE;
+
+if (!supabaseUrl || !supabaseServiceRole) {
+  throw new Error("Missing Supabase configuration");
+}
+
+const supabase = createClient(supabaseUrl, supabaseServiceRole);
+
+export default async function handler(req: any, res: any) {
+  try {
+    const { user_id, arm_id, action } = req.body;
+
+    if (!user_id) {
+      return res.status(400).json({ error: "Missing user_id" });
+    }
+
+    if (req.method === "GET") {
+      // Get all followed arms for a user
+      const { data, error } = await supabase
+        .from("user_followed_arms")
+        .select("arm_id")
+        .eq("user_id", user_id);
+
+      if (error) {
+        console.error("[Followed Arms API] Query error:", error);
+        return res.status(500).json({ error: error.message });
+      }
+
+      return res.status(200).json({
+        followedArms: (data || []).map((row: any) => row.arm_id),
+      });
+    } else if (req.method === "POST") {
+      // Follow or unfollow an arm
+      if (!arm_id || !action || !["follow", "unfollow"].includes(action)) {
+        return res.status(400).json({
+          error: "Missing or invalid parameters: arm_id, action (follow/unfollow)",
+        });
+      }
+
+      const validArms = ["labs", "gameforge", "corp", "foundation", "devlink", "nexus", "staff"];
+      if (!validArms.includes(arm_id)) {
+        return res.status(400).json({
+          error: `Invalid arm_id. Must be one of: ${validArms.join(", ")}`,
+        });
+      }
+
+      if (action === "follow") {
+        // Follow arm
+        const { error } = await supabase.from("user_followed_arms").insert({
+          user_id,
+          arm_id,
+        });
+
+        if (error) {
+          if (error.code === "23505") {
+            // Unique constraint violation - already following
+            return res.status(200).json({
+              message: "Already following this arm",
+              arm_id,
+            });
+          }
+          console.error("[Followed Arms API] Insert error:", error);
+          return res.status(500).json({ error: error.message });
+        }
+
+        return res.status(200).json({
+          message: "Arm followed successfully",
+          arm_id,
+        });
+      } else {
+        // Unfollow arm
+        const { error } = await supabase
+          .from("user_followed_arms")
+          .delete()
+          .eq("user_id", user_id)
+          .eq("arm_id", arm_id);
+
+        if (error) {
+          console.error("[Followed Arms API] Delete error:", error);
+          return res.status(500).json({ error: error.message });
+        }
+
+        return res.status(200).json({
+          message: "Arm unfollowed successfully",
+          arm_id,
+        });
+      }
+    } else {
+      return res.status(405).json({ error: "Method not allowed" });
+    }
+  } catch (error: any) {
+    console.error("[Followed Arms API] Unexpected error:", error);
+    return res.status(500).json({ error: error.message || "Internal server error" });
+  }
+}