> ## Documentation Index
> Fetch the complete documentation index at: https://docs.storagesync.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Presigned Urls

> Presigned Urls to upload files to StorageSync

This step assumes you have followed the [installation](/sdks/typescript/installation) steps and initialized the client.

## Why Presigned Urls?

Very rarely should you allow users to download or upload files from/to your bucket directly. This is because it is a security risk and can lead to malicious users accessing your bucket.

Instead, you should use **presigned** urls. Presigned urls are valid for a limited time and can be used to download or upload files.

## Create a Presigned Url using the StorageSyncClient

The example belows shows how we would create a presigned url for an object called list-of-cats.txt. This assumes the object exists in the root of your bucket.

## (Download) Create a Presigned Url using the SDK to Download a file.

```ts index.ts theme={null}
import { StorageSyncClient } from "@storagesync/client";

export async function getPresignedUrl() {
  const client = new StorageSyncClient({
    apiKey: "<YOUR_API_KEY>",
    bucket: "<YOUR_BUCKET_NAME>",
  });

  const url = await client.sign({
    key: "list-of-cats.txt",
    method: "GET",
    expires: 60 * 60, // Expires in 1 hour
  });

  return url;
}
```

Now the url can be used to allow users to download a file.

Check out our guides/examples to see how you could use this url in your application.

## (Upload) Create a Presigned Url using the SDK to Upload a file.

```ts index.ts theme={null}
import { StorageSyncClient } from "@storagesync/client";

export async function putPresignedUrl() {
  const client = new StorageSyncClient({
    apiKey: "<YOUR_API_KEY>",
    bucket: "<YOUR_BUCKET_NAME>",
  });

  const url = await client.sign({
    key: "list-of-cats.txt",
    method: "PUT",
    expires: 60 * 60, // Expires in 1 hour
  });

  return url;
}
```

Now the url can be used to allow users to upload a file.

Check out our guides/examples to see how you could use this url in your application.