diff --git a/bun.lock b/bun.lock
index 1c1f8a4..ff3f6e1 100644
--- a/bun.lock
+++ b/bun.lock
@@ -6,6 +6,7 @@
       "dependencies": {
         "axios": "^1.9.0",
         "cors": "^2.8.5",
+        "crypto": "^1.0.1",
         "dotenv": "^16.5.0",
         "express": "^5.1.0",
         "p-limit": "^6.2.0",
@@ -104,6 +105,8 @@
 
     "cors": ["cors@2.8.5", "", { "dependencies": { "object-assign": "^4", "vary": "^1" } }, "sha512-KIHbLJqu73RGr/hnbrO9uBeixNGuvSQjul/jdFvS/KFSIH1hWVd1ng7zOHx+YrEfInLG7q4n6GHQ9cDtxv/P6g=="],
 
+    "crypto": ["crypto@1.0.1", "", {}, "sha512-VxBKmeNcqQdiUQUW2Tzq0t377b54N2bMtXO/qiLa+6eRRmmC4qT3D4OnTGoT/U6O9aklQ/jTwbOtRMTTY8G0Ig=="],
+
     "debug": ["debug@4.4.0", "", { "dependencies": { "ms": "^2.1.3" } }, "sha512-6WTZ/IxCY/T6BALoZHaE4ctp9xm+Z5kY/pzYaCHRFeyVhojxlrm+46y68HA6hr0TcwEssoxNiDEUJQjfPZ/RYA=="],
 
     "delayed-stream": ["delayed-stream@1.0.0", "", {}, "sha512-ZySD7Nf91aLB0RxL4KGrKHBXl7Eds1DAmEdcoVawXnLD7SDhpNgtuII2aAkg7a7QS41jxPSZ17p4VdGnMHk3MQ=="],
diff --git a/engage-api/struct-activity.ts b/engage-api/struct-activity.ts
index 4d6fb28..c35b12b 100644
--- a/engage-api/struct-activity.ts
+++ b/engage-api/struct-activity.ts
@@ -254,4 +254,4 @@ export async function structActivityData(rawActivityData: RawActivityData): Prom
   }
   await postProcess(structuredActivityData);
   return structuredActivityData;
-}
+}
\ No newline at end of file
diff --git a/index.ts b/index.ts
index bc05eab..b25f58b 100644
--- a/index.ts
+++ b/index.ts
@@ -412,7 +412,7 @@ async function performBackgroundTasks(): Promise<void> {
   }
 }
 
-// --- Start Server and Background Tasks ---
+// Start Server and Background Tasks
 async function startServer(): Promise<void> {
   const redis = getRedisClient();
   if (!redis) {
diff --git a/package.json b/package.json
index 5637a2d..80197f0 100644
--- a/package.json
+++ b/package.json
@@ -14,6 +14,7 @@
   "dependencies": {
     "axios": "^1.9.0",
     "cors": "^2.8.5",
+    "crypto": "^1.0.1",
     "dotenv": "^16.5.0",
     "express": "^5.1.0",
     "p-limit": "^6.2.0",
diff --git a/services/s3-service.ts b/services/s3-service.ts
index 37c0abb..c620d75 100644
--- a/services/s3-service.ts
+++ b/services/s3-service.ts
@@ -3,6 +3,7 @@ import { S3Client } from "bun";
 import { v4 as uuidv4 } from 'uuid';
 import { config } from 'dotenv';
 import sharp from 'sharp';
+import crypto from 'crypto';
 import { logger } from '../utils/logger';
 import { decodeBase64Image } from '../utils/image-processor';
 
@@ -38,9 +39,10 @@ if (S3_ACCESS_KEY_ID && S3_SECRET_ACCESS_KEY && BUCKET_NAME) {
 
 /**
  * Uploads an image from a base64 string to S3, converting it to AVIF format.
+ * Uses MD5 checksum as filename and checks for duplicates before uploading.
  * @param base64Data - The base64 content (without the data URI prefix)
  * @param originalFormat - The image format (e.g., 'png', 'jpeg')
- * @param activityId - The activity ID, used for naming
+ * @param activityId - The activity ID, used for logging purposes
  * @returns The public URL of the uploaded image or null on error
  */
 export async function uploadImageFromBase64(
@@ -56,7 +58,6 @@ export async function uploadImageFromBase64(
     logger.error('S3 Upload: Missing base64Data, originalFormat, or activityId');
     return null;
   }
-
   try {
     // First decode the base64 image
     const imageBuffer = decodeBase64Image(base64Data);
@@ -69,18 +70,26 @@ export async function uploadImageFromBase64(
         // effort: 4,
       })
       .toBuffer();
-    // Use .avif extension for the object key
-    const objectKey = `${PUBLIC_URL_FILE_PREFIX}/activity-${activityId}-${uuidv4()}.avif`;
-    // Using Bun's S3Client file API
+    // Calculate MD5 checksum of the converted AVIF image
+    const md5Hash = crypto.createHash('md5').update(avifBuffer).digest('hex');
+    const objectKey = `${PUBLIC_URL_FILE_PREFIX}/${md5Hash}.avif`;
+    // Check if file with this checksum already exists
     const s3File = s3Client.file(objectKey);
+    const exists = await s3File.exists();
     
+    if (exists) {
+      const publicUrl = constructS3Url(objectKey);
+      logger.info(`Image already exists in S3 (MD5: ${md5Hash}), returning existing URL: ${publicUrl}`);
+      return publicUrl;
+    }
+    // File doesn't exist, proceed with upload
     await s3File.write(avifBuffer, {
       type: 'image/avif',
       acl: 'public-read'
     });
     
     const publicUrl = constructS3Url(objectKey);
-    logger.info(`Image uploaded to S3 as AVIF: ${publicUrl}`);
+    logger.info(`Image uploaded to S3 as AVIF (MD5: ${md5Hash}): ${publicUrl}`);
     return publicUrl;
   } catch (error) {
     logger.error(`S3 Upload Error for activity ${activityId}:`, error);
@@ -113,7 +122,6 @@ export async function listS3Objects(prefix: string): Promise<string[]> {
         startAfter,
         maxKeys: 1000
       });
-      
       if (result.contents) {
         // Add keys to our array, filtering out "directories"
         result.contents.forEach(item => {
@@ -126,14 +134,12 @@ export async function listS3Objects(prefix: string): Promise<string[]> {
           startAfter = result.contents[result.contents.length - 1]?.key;
         }
       }
-      
       isTruncated = result.isTruncated || false;
       // Safety check to prevent infinite loops
       if (result.contents?.length === 0) {
         break;
       }
     }
-    
     logger.info(`Listed ${objectKeys.length} object keys from S3 with prefix "${prefix}"`);
     return objectKeys;
   } catch (error) {
@@ -156,7 +162,6 @@ export async function deleteS3Objects(objectKeysArray: string[]): Promise<boolea
     logger.info('No objects to delete from S3.');
     return true;
   }
-
   try {
     // With Bun's S3Client, we need to delete objects one by one
     // Process in batches of 100 for better performance
@@ -180,7 +185,6 @@ export async function deleteS3Objects(objectKeysArray: string[]): Promise<boolea
         }
       }
     }
-    
     logger.info(`Deleted ${successCount} objects from S3. Failed: ${errorCount}`);
     return errorCount === 0; // True if all succeeded
   } catch (error) {