Get a signed PUT URL for file uploading

Use this API to generate a pre-signed PUT URL for uploading files larger than 10MB, which exceeds FormX's direct file upload limit.

When to use this API:

• Files ≤10MB: Upload directly to extraction endpoints (e.g., /v2/extract)
• Files >10MB: Use this API to get a signed URL, then upload your file via PUT request

Upload workflow for large files:

1. Call this API with the file size, filename, and content type
2. Receive a pre-signed PUT URL in the response
3. Upload your file to the signed URL using an HTTP PUT request
4. Use the file reference in subsequent API calls (e.g., extraction)

The signed URL is temporary and will expire after a set period. The maximum file size is 524,288,000 bytes (~500MB).

Body Parameters:

• size (required): File size in bytes (1 to 524,288,000)
• filename (optional): Name of the file to be uploaded
• content_type (optional): MIME type of the file (e.g., "application/pdf", "image/jpeg")