diff --git a/lib/block-service.ts b/lib/block-service.ts
new file mode 100644
index 0000000..9288267
--- /dev/null
+++ b/lib/block-service.ts
@@ -0,0 +1,35 @@
+import { getSelf } from "./auth-service";
+import { db } from "./db";
+
+export const isBlockedByUser = async (id: string) => {
+  try {
+    const self = await getSelf();
+
+    const otherUser = await db.user.findUnique({
+      where: {
+        id,
+      },
+    });
+
+    if (!otherUser) {
+      throw new Error("User not found");
+    }
+
+    if (otherUser.id === self.id) {
+      return false;
+    }
+
+    const existingBlock = await db.block.findUnique({
+      where: {
+        blockerId_blockedId: {
+          blockerId: otherUser.id,
+          blockedId: self.id,
+        },
+      },
+    });
+
+    return !!existingBlock;
+  } catch {
+    return false;
+  }
+};