# Serving assets from Storage

Serving assets from Storage

## Public buckets

As mentioned in the [Buckets Fundamentals](/docs/guides/storage/buckets/fundamentals) all files uploaded in a public bucket are publicly accessible and benefit a high CDN cache HIT ratio.

You can access them by using this conventional URL:

```
https://[project_id].supabase.co/storage/v1/object/public/[bucket]/[asset-name]
```

You can also use the Supabase SDK `getPublicUrl` to generate this URL for you

```js
import { createClient } from '@supabase/supabase-js'

const supabase = createClient('your_project_url', 'your_supabase_api_key')

// ---cut---
const { data } = supabase.storage.from('bucket').getPublicUrl('filePath.jpg')

console.log(data.publicUrl)
```

### Downloading

If you want the browser to start an automatic download of the asset instead of trying serving it, you can add the `?download` query string parameter.

By default it will use the asset name to save the file on disk. You can optionally pass a custom name to the `download` parameter as following: `?download=customname.jpg`

#### Programmatic downloads with query parameters

When using the SDK's `download()` method, you can pass additional query parameters to customize the download behavior:

**JavaScript**

```js
import { createClient } from '@supabase/supabase-js'

const supabase = createClient('your_project_url', 'your_supabase_api_key')

// ---cut---
// Download with custom filename
const { data, error } = await supabase.storage.from('avatars').download('avatar1.png', {
  download: 'my-custom-name.png',
})
```

**Dart**

```dart
// Download with additional query parameters
final response = await supabase.storage
  .from('avatars')
  .download(
    'avatar1.png',
    queryParams: {
      'download': 'my-custom-name.png',
    },
  );
```

[Reference.](/docs/reference/dart/file-buckets-download)

**Swift**

```swift
// Download with additional query parameters
let response = try await supabase.storage
  .from("avatars")
  .download(
    path: "avatar1.png",
    queryItems: [
      URLQueryItem(name: "download", value: "my-custom-name.png")
    ]
  )
```

[Reference.](/docs/reference/swift/storage-from-download)

## Private buckets

Assets stored in a non-public bucket are considered private and are not accessible via a public URL like the public buckets.

You can access them only by:

- Signing a time limited URL on the Server, for example with Edge Functions.
- with a GET request the URL `https://[project_id].supabase.co/storage/v1/object/authenticated/[bucket]/[asset-name]` and the user Authorization header

### Signing URLs

Note: Storage signed URLs are signed with a dedicated internal key that is separate from your project's Auth JWT signing key. Each project has its own signing key.

Because signed URLs use this separate key, they are not affected by:

- Rotating or revoking Auth JWT legacy secret or signing key
- Disabling legacy keys in the dashboard
- Switching from HS256 to asymmetric (ES256) signing key

Signed URLs remain valid until their expiry time regardless of any Auth key changes.

If you need to revoke signed URLs, [contact Supabase support](/dashboard/support/new?projectRef=).

You can sign a time-limited URL that you can share to your users by invoking the `createSignedUrl` method on the SDK.

```js
import { createClient } from '@supabase/supabase-js'

const supabase = createClient('your_project_url', 'your_supabase_api_key')

// ---cut---
const { data, error } = await supabase.storage
  .from('bucket')
  .createSignedUrl('private-document.pdf', 3600)

if (data) {
  console.log(data.signedUrl)
}
```