diff --git a/package-lock.json b/package-lock.json
index 7fa9def..253fa91 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@insforge/cli",
-  "version": "0.1.90",
+  "version": "0.1.91",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@insforge/cli",
-      "version": "0.1.90",
+      "version": "0.1.91",
       "license": "Apache-2.0",
       "dependencies": {
         "@clack/prompts": "^0.9.1",
diff --git a/package.json b/package.json
index 6e2c85b..2568a7d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@insforge/cli",
-  "version": "0.1.90",
+  "version": "0.1.91",
   "description": "InsForge CLI - Command line tool for InsForge platform",
   "type": "module",
   "bin": {
diff --git a/src/commands/storage/upload.test.ts b/src/commands/storage/upload.test.ts
new file mode 100644
index 0000000..9a546b0
--- /dev/null
+++ b/src/commands/storage/upload.test.ts
@@ -0,0 +1,23 @@
+import { describe, it, expect } from 'vitest';
+import { resolveUploadContentType } from './upload.js';
+
+describe('resolveUploadContentType', () => {
+  it('uses an explicit --content-type over inference', () => {
+    expect(resolveUploadContentType('photo.png', 'image/webp')).toBe('image/webp');
+  });
+
+  it('infers from the file extension when no flag is given', () => {
+    expect(resolveUploadContentType('photo.png')).toBe('image/png');
+    expect(resolveUploadContentType('/tmp/report.pdf')).toBe('application/pdf');
+  });
+
+  it('treats an empty or whitespace flag as not provided', () => {
+    expect(resolveUploadContentType('photo.png', '')).toBe('image/png');
+    expect(resolveUploadContentType('photo.png', '   ')).toBe('image/png');
+  });
+
+  it('falls back to octet-stream for an unknown extension', () => {
+    expect(resolveUploadContentType('archive.unknownext')).toBe('application/octet-stream');
+    expect(resolveUploadContentType('noext')).toBe('application/octet-stream');
+  });
+});
diff --git a/src/commands/storage/upload.ts b/src/commands/storage/upload.ts
index 66ed104..3849b83 100644
--- a/src/commands/storage/upload.ts
+++ b/src/commands/storage/upload.ts
@@ -5,6 +5,16 @@ import { getProjectConfig } from '../../lib/config.js';
 import { requireAuth } from '../../lib/credentials.js';
 import { handleError, getRootOpts, CLIError, ProjectNotLinkedError } from '../../lib/errors.js';
 import { outputJson, outputSuccess } from '../../lib/output.js';
+import { mimeTypeFromName } from '../../lib/mime.js';
+
+/**
+ * Resolve the content type for an upload: an explicit (non-empty) `--content-type`
+ * wins, otherwise infer from the file extension, otherwise fall back to the
+ * storage default. Exported for testing.
+ */
+export function resolveUploadContentType(filePath: string, explicit?: string): string {
+  return explicit?.trim() || mimeTypeFromName(filePath) || 'application/octet-stream';
+}
 
 export function registerStorageUploadCommand(storageCmd: Command): void {
   storageCmd
@@ -12,6 +22,7 @@ export function registerStorageUploadCommand(storageCmd: Command): void {
     .description('Upload a file to a storage bucket')
     .requiredOption('--bucket <name>', 'Target bucket name')
     .option('--key <objectKey>', 'Object key (defaults to filename)')
+    .option('--content-type <type>', 'MIME type to store (defaults to one inferred from the file extension)')
     .action(async (file: string, opts, cmd) => {
       const { json } = getRootOpts(cmd);
       try {
@@ -28,9 +39,15 @@ export function registerStorageUploadCommand(storageCmd: Command): void {
         const objectKey = opts.key ?? basename(file);
         const bucketName = opts.bucket;
 
-        // Build multipart form data
+        // Resolve the content type: explicit flag wins, then infer from the
+        // file's extension. Without this a typeless Blob is stored as
+        // application/octet-stream regardless of the actual file type.
+        const contentType = resolveUploadContentType(file, opts.contentType);
+
+        // Build multipart form data. The Blob's type becomes the multipart
+        // part's Content-Type, which the backend stores as the object's MIME type.
         const formData = new FormData();
-        const blob = new Blob([fileContent]);
+        const blob = new Blob([fileContent], { type: contentType });
         formData.append('file', blob, objectKey);
 
         // PUT /api/storage/buckets/{bucket}/objects/{key} for named upload
diff --git a/src/lib/mime.test.ts b/src/lib/mime.test.ts
new file mode 100644
index 0000000..c688f60
--- /dev/null
+++ b/src/lib/mime.test.ts
@@ -0,0 +1,31 @@
+import { describe, it, expect } from 'vitest';
+import { mimeTypeFromName } from './mime.js';
+
+describe('mimeTypeFromName', () => {
+  it('infers common types from the extension', () => {
+    expect(mimeTypeFromName('photo.png')).toBe('image/png');
+    expect(mimeTypeFromName('a.jpeg')).toBe('image/jpeg');
+    expect(mimeTypeFromName('report.pdf')).toBe('application/pdf');
+    expect(mimeTypeFromName('data.json')).toBe('application/json');
+    expect(mimeTypeFromName('clip.mp4')).toBe('video/mp4');
+  });
+
+  it('is case-insensitive and handles full paths', () => {
+    expect(mimeTypeFromName('IMG.PNG')).toBe('image/png');
+    expect(mimeTypeFromName('/tmp/sub dir/cover.JPG')).toBe('image/jpeg');
+    expect(mimeTypeFromName('archive.tar.gz')).toBe('application/gzip');
+  });
+
+  it('ignores dots in parent directories (basename only)', () => {
+    expect(mimeTypeFromName('/home/user.name/photo.png')).toBe('image/png');
+    expect(mimeTypeFromName('/home/user.name/datafile')).toBeUndefined();
+    expect(mimeTypeFromName('C:\\Users\\a.b\\report.pdf')).toBe('application/pdf');
+  });
+
+  it('returns undefined for unknown or missing extensions', () => {
+    expect(mimeTypeFromName('file.unknownext')).toBeUndefined();
+    expect(mimeTypeFromName('noext')).toBeUndefined();
+    expect(mimeTypeFromName('trailingdot.')).toBeUndefined();
+    expect(mimeTypeFromName('.gitignore')).toBeUndefined();
+  });
+});
diff --git a/src/lib/mime.ts b/src/lib/mime.ts
new file mode 100644
index 0000000..ae90479
--- /dev/null
+++ b/src/lib/mime.ts
@@ -0,0 +1,85 @@
+/**
+ * Minimal extension → MIME type lookup for storage uploads.
+ *
+ * The CLI reads raw bytes off disk, so unlike a browser `File` there is no
+ * `type` to read — without inference every upload would be stored as
+ * `application/octet-stream`. We infer from the filename extension (the same
+ * approach `aws s3 cp` uses). Unknown extensions fall back to octet-stream,
+ * which is the server's default anyway, so this is strictly an improvement.
+ */
+
+const EXTENSION_MIME_TYPES: Record<string, string> = {
+  // Images
+  png: 'image/png',
+  jpg: 'image/jpeg',
+  jpeg: 'image/jpeg',
+  gif: 'image/gif',
+  webp: 'image/webp',
+  svg: 'image/svg+xml',
+  bmp: 'image/bmp',
+  ico: 'image/x-icon',
+  avif: 'image/avif',
+  heic: 'image/heic',
+  heif: 'image/heif',
+  tif: 'image/tiff',
+  tiff: 'image/tiff',
+  // Documents
+  pdf: 'application/pdf',
+  doc: 'application/msword',
+  docx: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+  xls: 'application/vnd.ms-excel',
+  xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+  ppt: 'application/vnd.ms-powerpoint',
+  pptx: 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+  // Text / data
+  txt: 'text/plain',
+  csv: 'text/csv',
+  md: 'text/markdown',
+  html: 'text/html',
+  htm: 'text/html',
+  css: 'text/css',
+  js: 'text/javascript',
+  mjs: 'text/javascript',
+  json: 'application/json',
+  xml: 'application/xml',
+  yaml: 'application/yaml',
+  yml: 'application/yaml',
+  // Archives
+  zip: 'application/zip',
+  gz: 'application/gzip',
+  tar: 'application/x-tar',
+  rar: 'application/vnd.rar',
+  '7z': 'application/x-7z-compressed',
+  // Audio
+  mp3: 'audio/mpeg',
+  wav: 'audio/wav',
+  ogg: 'audio/ogg',
+  m4a: 'audio/mp4',
+  flac: 'audio/flac',
+  aac: 'audio/aac',
+  // Video
+  mp4: 'video/mp4',
+  webm: 'video/webm',
+  mov: 'video/quicktime',
+  avi: 'video/x-msvideo',
+  mkv: 'video/x-matroska',
+  // Fonts
+  woff: 'font/woff',
+  woff2: 'font/woff2',
+  ttf: 'font/ttf',
+  otf: 'font/otf',
+};
+
+/**
+ * Infer a MIME type from a filename/path extension. Returns `undefined` when the
+ * extension is missing or unrecognized.
+ */
+export function mimeTypeFromName(name: string): string | undefined {
+  // Strip any directory portion first so a dot in a parent directory
+  // (e.g. "/home/user.name/datafile") can't be mistaken for an extension.
+  const base = name.slice(Math.max(name.lastIndexOf('/'), name.lastIndexOf('\\')) + 1);
+  const lastDot = base.lastIndexOf('.');
+  if (lastDot < 0 || lastDot === base.length - 1) return undefined;
+  const ext = base.slice(lastDot + 1).toLowerCase();
+  return EXTENSION_MIME_TYPES[ext];
+}