diff --git a/.env.example b/.env.example
index 20b19199..362b7c23 100644
--- a/.env.example
+++ b/.env.example
@@ -29,6 +29,11 @@ API_KEY=your_api_key_here
 #S3_REGION=your-region
 #S3_BUCKET_NAME=your-bucket-name
 
+# optional
+# Purpose: S3_PUBLIC_URL custom domain for returned file URLs (e.g., CDN or Cloudflare R2 custom domain)
+# When set, file URLs will use this domain without the bucket name in the path
+#S3_PUBLIC_URL=https://subdomain.domain.com
+
 
 # Google Cloud Storage Env Variables
 #
diff --git a/CLAUDE.md b/CLAUDE.md
index 29062002..a5f8ea69 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -169,6 +169,7 @@ S3-Compatible:
 - `GUNICORN_TIMEOUT` - Worker timeout seconds (default: 30)
 - `GCP_JOB_NAME` - Cloud Run Job name for offloading
 - `GCP_JOB_LOCATION` - Cloud Run Job region (default: us-central1)
+- `S3_PUBLIC_URL` - Custom domain for S3 file URLs (e.g., "subdomain.domain.com"). When set, URLs exclude bucket name and use this domain instead of S3_ENDPOINT_URL
 
 ## Key Patterns
 
diff --git a/README.md b/README.md
index e97899b6..d7a5517e 100644
--- a/README.md
+++ b/README.md
@@ -162,6 +162,16 @@ Each endpoint is supported by robust payload validation and detailed API documen
 - **Purpose**: The region for the S3-compatible storage service.
 - **Requirement**: Mandatory if using S3-compatible storage, "None" is acceptible for some s3 providers.
 
+#### `S3_PUBLIC_URL`
+- **Purpose**: Custom domain to use as the base URL for all returned file URLs (e.g., CDN domain).
+- **Requirement**: Optional. When set, file URLs will use this domain instead of `S3_ENDPOINT_URL`, and the bucket name will be excluded from the URL path.
+- **Example**: Set to `subdomain.domain.com` to return URLs like `https://subdomain.domain.com/file.mp3` instead of `https://nyc3.digitaloceanspaces.com/bucket-name/file.mp3`
+- **Note**: The value can include or exclude the `https://` protocol prefix. If omitted, `https://` will be automatically prepended.
+- **Common Use Cases**:
+  1. **Cloudflare R2 Public Access**: Cloudflare R2 requires custom domains (without bucket names in the URL path) to serve files publicly without authentication. Set `S3_PUBLIC_URL` to your R2 custom domain to enable public file access.
+  2. **CDN Integration**: Use CloudFlare, AWS CloudFront, Fastly, or other CDNs in front of your S3 storage for improved performance, caching, and reduced bandwidth costs. Set `S3_PUBLIC_URL` to your CDN domain.
+  3. **Custom Domain Branding**: Use your own branded domain (e.g., `files.yourcompany.com`) instead of exposing the underlying cloud provider's domain in file URLs, providing a more professional appearance and easier domain migration.
+
 ---
 
 ### Google Cloud Storage (GCP) Environment Variables
diff --git a/config.py b/config.py
index 2b4e9826..4a1fad0d 100644
--- a/config.py
+++ b/config.py
@@ -31,6 +31,9 @@
 GCP_SA_CREDENTIALS = os.environ.get('GCP_SA_CREDENTIALS', '')
 GCP_BUCKET_NAME = os.environ.get('GCP_BUCKET_NAME', '')
 
+# S3 public URL override (optional) - when set, uses this as base URL instead of S3_ENDPOINT_URL
+S3_PUBLIC_URL = os.environ.get('S3_PUBLIC_URL', '')
+
 def validate_env_vars(provider):
 
     """ Validate the necessary environment variables for the selected storage provider """
diff --git a/docker-compose.md b/docker-compose.md
index 0c768648..cf0c47a2 100644
--- a/docker-compose.md
+++ b/docker-compose.md
@@ -140,6 +140,11 @@ API_KEY=your_api_key_here
 #S3_REGION=your-region
 #S3_BUCKET_NAME=your-bucket-name
 
+# optional
+# Purpose: S3_PUBLIC_URL custom domain for returned file URLs (e.g., CDN or Cloudflare R2 custom domain)
+# When set, file URLs will use this domain without the bucket name in the path
+#S3_PUBLIC_URL=https://subdomain.domain.com
+
 
 # Google Cloud Storage Env Variables
 #
diff --git a/docs/cloud-installation/do.md b/docs/cloud-installation/do.md
index 817c4c2c..644fc300 100644
--- a/docs/cloud-installation/do.md
+++ b/docs/cloud-installation/do.md
@@ -59,6 +59,8 @@ You'll need to create a Space (Digital Ocean's object storage) for the toolkit t
 
 Add the following environment variables exactly as shown (be careful with underscores vs. dashes and avoid any leading/trailing spaces):
 
+### Required Variables
+
 1. `API_KEY`: Your API key (e.g., `test123` for testing - change for production)
 2. `S3_ENDPOINT_URL`: The URL of your Space (copied from Step 3)
 3. `S3_ACCESS_KEY`: The access key from Step 3
@@ -66,6 +68,14 @@ Add the following environment variables exactly as shown (be careful with unders
 5. `S3_BUCKET_NAME`: The name of your Space bucket (e.g., `nca-toolkit-bucket`)
 6. `S3_REGION`: The region code of your Space (e.g., `NYC3` for New York)
 
+### Optional Variables
+
+7. `S3_PUBLIC_URL`: Custom domain for file URLs (e.g., `cdn.yourdomain.com`)
+   - Use this if you have a CDN or custom domain in front of your Space
+   - When set, returned file URLs will use this domain instead of the Digital Ocean Spaces URL
+   - The bucket name will be excluded from the URL path
+   - Example: If set to `files.example.com`, URLs will be `https://files.example.com/file.mp3` instead of `https://nyc3.digitaloceanspaces.com/bucket-name/file.mp3`
+
 ## Step 7: Finalize and Deploy
 
 1. For Deployment Region, select a region close to your location (e.g., San Francisco)
diff --git a/services/s3_toolkit.py b/services/s3_toolkit.py
index 1b0dc970..9e027830 100644
--- a/services/s3_toolkit.py
+++ b/services/s3_toolkit.py
@@ -42,7 +42,19 @@ def upload_to_s3(file_path, s3_url, access_key, secret_key, bucket_name, region)
 
         # URL encode the filename for the URL
         encoded_filename = quote(os.path.basename(file_path))
-        file_url = f"{s3_url}/{bucket_name}/{encoded_filename}"
+
+        # Check if S3_PUBLIC_URL is set for custom domain
+        public_url = os.getenv('S3_PUBLIC_URL', '').strip()
+        if public_url:
+            # Ensure https:// prefix if not present
+            if not public_url.startswith('http'):
+                public_url = f"https://{public_url}"
+            # Use public URL without bucket name
+            file_url = f"{public_url}/{encoded_filename}"
+        else:
+            # Use existing logic with bucket name
+            file_url = f"{s3_url}/{bucket_name}/{encoded_filename}"
+
         return file_url
     except Exception as e:
         logger.error(f"Error uploading file to S3: {e}")
diff --git a/services/v1/s3/upload.py b/services/v1/s3/upload.py
index 49fc3898..39ef0cb1 100644
--- a/services/v1/s3/upload.py
+++ b/services/v1/s3/upload.py
@@ -153,7 +153,18 @@ def stream_upload_to_s3(file_url, custom_filename=None, make_public=False, downl
         if make_public:
             # URL encode the filename for the URL only
             encoded_filename = quote(filename)
-            file_url = f"{endpoint_url}/{bucket_name}/{encoded_filename}"
+
+            # Check if S3_PUBLIC_URL is set for custom domain
+            public_url = os.getenv('S3_PUBLIC_URL', '').strip()
+            if public_url:
+                # Ensure https:// prefix if not present
+                if not public_url.startswith('http'):
+                    public_url = f"https://{public_url}"
+                # Use public URL without bucket name
+                file_url = f"{public_url}/{encoded_filename}"
+            else:
+                # Use existing logic with bucket name
+                file_url = f"{endpoint_url}/{bucket_name}/{encoded_filename}"
         else:
             # Generate a pre-signed URL for private files
             file_url = s3_client.generate_presigned_url(