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

# Create Presigned Upload

> Start a direct-to-storage upload with dreep.presignUpload(), for large files and browser clients.

Returns a short-lived URL to `PUT` the file bytes to. The file never passes through the
Dreep API, which is what makes this the right path for large files — and the only safe way
to upload from a browser, since your API key stays on your server.

```ts theme={null}
const upload = await dreep.presignUpload({
  filename: "video.mp4",
  contentType: "video/mp4",
  sizeBytes: 84_000_000,
  folder: "uploads/2026",
});
```

## Parameters

| Parameter           | Type          | Description                                                  |
| :------------------ | :------------ | :----------------------------------------------------------- |
| `contentType`       | `string`      | **Required.** MIME type of the file                          |
| `sizeBytes`         | `number`      | **Required.** Exact size in bytes                            |
| `filename`          | `string`      | Optional when `key` supplies the name                        |
| `folder`            | `string`      | Slug path of the destination. Missing folders are created    |
| `key`               | `string`      | Full S3-style object key                                     |
| `folderId`          | `string`      | UUID of an existing folder                                   |
| `autoCreateFolders` | `boolean`     | Set `false` to require the path already exists               |
| `format`            | `string`      | Target format to re-encode to on confirm                     |
| `presetKey`         | `string`      | A saved preset, applied on confirm                           |
| `contentHash`       | `string`      | SHA-256 of the file — lets Dreep skip content it already has |
| `signal`            | `AbortSignal` | Cancels the request                                          |

## Returns

```ts theme={null}
{
  id: "2f928a3f-1d2a-4a2b",
  uploadUrl: "https://…",   // absent when alreadyExists is true
  contentType: "video/mp4",
  alreadyExists: false,
}
```

## The full flow

```ts theme={null}
// 1. On your server
const upload = await dreep.presignUpload({ filename, contentType, sizeBytes });

// 2. Anywhere, including the browser
await fetch(upload.uploadUrl, { method: "PUT", body: file });

// 3. On your server
const asset = await dreep.confirmUpload({ id: upload.id });
```

Until [`confirmUpload()`](/node-sdk/upload/confirm-upload) is called the asset stays
`pending` and is excluded from media listings.

<Warning>
  The `PUT` must use the exact `contentType` and `sizeBytes` you presigned with — the
  signature covers both. See [Uploading Media](/guides/uploading) for the underlying HTTP
  flow.
</Warning>

## Skipping duplicate uploads

Pass the file's SHA-256 as `contentHash`. If Dreep already stores that content, the
response comes back with `alreadyExists: true` and no `uploadUrl` — skip the `PUT`.

```ts theme={null}
const upload = await dreep.presignUpload({ contentType, sizeBytes, contentHash });

if (!upload.alreadyExists) {
  await fetch(upload.uploadUrl!, { method: "PUT", body: file });
}

const asset = await dreep.confirmUpload({ id: upload.id });
```