# Get upload url upload url

`POST` `/api/v1/assets/upload-url`

Returns a pre-signed S3 URL and an upload token. PUT the file bytes
directly to the URL, then call complete_asset_upload with the token to
create the data source.

Example upload step:
    curl -X PUT "<upload_url>" --upload-file "/path/to/file.csv"

For Excel files, pass sheet_index (0-based) to select which sheet to
convert to CSV.

## Request body

`application/json`

| Field | Type | Required | Description |
|-------|------|----------|-------------|
| file_name | string | yes | File name including extension (e.g. 'accounts.csv' or 'data.xlsx') |
| sheet_index | integer | no | Sheet index (0-based) to convert for Excel files |

## Response

`200 OK` — `application/json`

| Field | Type | Description |
|-------|------|-------------|
| upload_url | string | Pre-signed S3 URL — PUT the file bytes directly to this URL |
| upload_token | string | Opaque token to pass to complete_upload after the PUT succeeds |
| expires_in | integer | Seconds until the upload URL and token expire |

## Errors

| Status | Description |
|--------|-------------|
| 400 | Bad Request |
| 422 | Unprocessable Entity |