diff --git a/backend/src/upload/upload.service.ts b/backend/src/upload/upload.service.ts
index 4044561..14c05d2 100644
--- a/backend/src/upload/upload.service.ts
+++ b/backend/src/upload/upload.service.ts
@@ -21,14 +21,20 @@ import { getPrivateS3Url } from 'src/common/helper';
 @Injectable()
 export class UploadService {
   private s3: S3Client;
+
+  // Separate client for generating presigned URLs that browsers can reach.
+  // Uses the public-facing FRONTEND_URL instead of the internal MinIO endpoint
+  // so presigned URLs are https://domain/bucket/key instead of http://minio:9000/...
+  private presignS3: S3Client;
+
   constructor() {
-    const s3Config: any = {
-      region: process.env.AWS_REGION || 'us-east-1',
-      credentials: {
-        accessKeyId: process.env.AWS_ACCESS_KEY,
-        secretAccessKey: process.env.AWS_SECRET_KEY,
-      },
+    const credentials = {
+      accessKeyId: process.env.AWS_ACCESS_KEY,
+      secretAccessKey: process.env.AWS_SECRET_KEY,
     };
+    const region = process.env.AWS_REGION || 'us-east-1';
+
+    const s3Config: any = { region, credentials };
 
     // MinIO compatibility: if S3_ENDPOINT is set, override the endpoint
     // and force path-style access (MinIO requires this)
@@ -38,6 +44,21 @@ export class UploadService {
     }
 
     this.s3 = new S3Client(s3Config);
+
+    // For presigned URLs served to the browser, use the public domain
+    // so URLs are reachable over HTTPS (avoids Mixed Content errors).
+    // Nginx proxies /indeedhub-*/ paths to MinIO internally.
+    const presignEndpoint = process.env.FRONTEND_URL;
+    if (presignEndpoint && process.env.S3_ENDPOINT) {
+      this.presignS3 = new S3Client({
+        region,
+        credentials,
+        endpoint: presignEndpoint,
+        forcePathStyle: true,
+      });
+    } else {
+      this.presignS3 = this.s3;
+    }
   }
 
   async initialize({
@@ -72,7 +93,7 @@ export class UploadService {
         PartNumber: index + 1,
       });
       promises.push(
-        getSignedUrl(this.s3, command, {
+        getSignedUrl(this.presignS3, command, {
           expiresIn: 60 * 60 * 24 * 7,
         }),
       );
@@ -180,7 +201,7 @@ export class UploadService {
         Bucket: process.env.S3_PRIVATE_BUCKET_NAME,
         Key: key,
       });
-      return getSignedUrl(this.s3, command, {
+      return getSignedUrl(this.presignS3, command, {
         expiresIn: expires ?? 60 * 60 * 24 * 7,
       });
     }
diff --git a/docker-compose.yml b/docker-compose.yml
index 940ff3e..7505098 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -20,7 +20,7 @@ services:
       context: .
       dockerfile: Dockerfile
       args:
-        CACHEBUST: "8"
+        CACHEBUST: "9"
         VITE_USE_MOCK_DATA: "false"
         VITE_CONTENT_ORIGIN: ${FRONTEND_URL}
         VITE_INDEEHUB_API_URL: /api
@@ -47,7 +47,7 @@ services:
       context: ./backend
       dockerfile: Dockerfile
       args:
-        CACHEBUST: "8"
+        CACHEBUST: "9"
     restart: unless-stopped
     environment:
       # ── Core ─────────────────────────────────────────────
@@ -179,7 +179,7 @@ services:
       context: ./backend
       dockerfile: Dockerfile.ffmpeg
       args:
-        CACHEBUST: "8"
+        CACHEBUST: "9"
     restart: unless-stopped
     environment:
       ENVIRONMENT: production
diff --git a/nginx.conf b/nginx.conf
index 82747f1..604a245 100644
--- a/nginx.conf
+++ b/nginx.conf
@@ -84,6 +84,29 @@ server {
         add_header Cache-Control "no-store";
     }
 
+    # ── MinIO direct proxy (for presigned URL uploads/downloads) ──
+    # The backend generates presigned URLs pointing to the public domain.
+    # This location proxies those requests to MinIO WITHOUT rewriting the
+    # path, so the S3v4 signature (which includes the path) stays valid.
+    location ~ ^/(indeedhub-private|indeedhub-public)/ {
+        resolver 127.0.0.11 valid=30s ipv6=off;
+        set $minio_upstream http://minio:9000;
+
+        proxy_pass $minio_upstream;
+        proxy_http_version 1.1;
+        # Pass the original Host so MinIO's signature verification matches
+        # the host the presigned URL was generated for.
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+
+        # Allow large file uploads (up to 5GB per chunk)
+        client_max_body_size 5g;
+
+        # No caching for upload responses
+        add_header Cache-Control "no-store";
+    }
+
     # ── WebSocket proxy to Nostr relay (Docker service) ────────
     location /relay {
         resolver 127.0.0.11 valid=30s ipv6=off;