diff --git a/backend/constants.py b/backend/constants.py
new file mode 100644
index 0000000..b9dfac2
--- /dev/null
+++ b/backend/constants.py
@@ -0,0 +1 @@
+MAX_BLOOM_LENGTH = 280
\ No newline at end of file
diff --git a/backend/endpoints.py b/backend/endpoints.py
index 0e177a0..892478e 100644
--- a/backend/endpoints.py
+++ b/backend/endpoints.py
@@ -1,3 +1,4 @@
+from constants import MAX_BLOOM_LENGTH
 from typing import Dict, Union
 from data import blooms
 from data.follows import follow, get_followed_usernames, get_inverse_followed_usernames
@@ -157,6 +158,10 @@ def send_bloom():
         return type_check_error
 
     user = get_current_user()
+    #  Check server-side length 
+    content=request.json["content"]
+    if len(content)>MAX_BLOOM_LENGTH :
+        return jsonify({"success": False, "error": f"Bloom must be {MAX_BLOOM_LENGTH} characters or less"}), 400
 
     blooms.add_bloom(sender=user, content=request.json["content"])
 
diff --git a/front-end/lib/api.mjs b/front-end/lib/api.mjs
index f4b5339..5018ecf 100644
--- a/front-end/lib/api.mjs
+++ b/front-end/lib/api.mjs
@@ -1,5 +1,8 @@
 import {state} from "../index.mjs";
 import {handleErrorDialog} from "../components/error.mjs";
+import { MAX_BLOOM_LENGTH } from "./constants.mjs";
+
+
 
 // === ABOUT THE STATE
 // state gives you these two functions only
@@ -194,10 +197,18 @@ async function getBloomsByHashtag(hashtag) {
 }
 
 async function postBloom(content) {
+  // Check client-side length first
+  if (content.length>MAX_BLOOM_LENGTH){
+    handleErrorDialog(
+      new Error(`Bloom must be ${MAX_BLOOM_LENGTH} characters or less`),
+    );
+    return { success: false };
+
+  }
   try {
     const data = await _apiRequest("/bloom", {
       method: "POST",
-      body: JSON.stringify({content}),
+      body: JSON.stringify({ content }),
     });
 
     if (data.success) {
@@ -208,7 +219,7 @@ async function postBloom(content) {
     return data;
   } catch (error) {
     // Error already handled by _apiRequest
-    return {success: false};
+    return { success: false };
   }
 }
 
diff --git a/front-end/lib/constants.mjs b/front-end/lib/constants.mjs
new file mode 100644
index 0000000..dc4099f
--- /dev/null
+++ b/front-end/lib/constants.mjs
@@ -0,0 +1 @@
+export const MAX_BLOOM_LENGTH = 280;
diff --git a/front-end/tests/bloom-length.spec.js b/front-end/tests/bloom-length.spec.js
new file mode 100644
index 0000000..73442a9
--- /dev/null
+++ b/front-end/tests/bloom-length.spec.js
@@ -0,0 +1,36 @@
+import { test, expect } from "@playwright/test";
+import { loginAsSample } from "./test-utils";
+import { MAX_BLOOM_LENGTH } from "../lib/constants.mjs";
+
+
+
+test(`server should reject blooms longer than ${MAX_BLOOM_LENGTH} characters`, async ({
+  page,
+}) => {
+  await loginAsSample(page);
+
+  const longBloom = "A".repeat(MAX_BLOOM_LENGTH + 1);
+
+  const result = await page.evaluate(async (content) => {
+    const res = await fetch("/bloom", {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json",
+      },
+      credentials: "include",
+      body: JSON.stringify({ content }),
+    });
+
+    if (!res.ok) {
+      try {
+        return await res.json();
+      } catch {
+        return { success: false };
+      }
+    }
+
+    return await res.json();
+  }, longBloom);
+
+  expect(result.success).toBe(false);
+});