API v1 preview

# The File object

A registered file and its temporary upload instructions.

## Fields

`id` string · required

Unique, server-generated file ID. Treat it as an opaque reference.

Min length: 37 · Max length: 37

`upload` object · required

Temporary upload instructions. Send all fields unchanged, then append the file as the last form field. Do not send your API key to storage.

**upload fields**

`method` string · required

Allowed values: POST

`url` string (uri) · required

Destination for the file upload. Authorization is carried in the signed form fields.

`fields` object · required

Complete generated form fields, including the object key, policy, signature, and AWS verification fields. Treat this map as opaque and forward every field unchanged. The actual file is supplied separately.

`expires_at` string (date-time) · required

UTC expiration of these upload instructions, at most one hour after issuance. Retrying does not extend it. Completed uploads remain usable until the file’s unlinked retention deadline.

## Returned by

- [Create a file](https://ottomfg.com/docs/create-file.md)

Example

JSON

```
{
  "upload": {
    "method": "POST",
    "url": "https://example-upload-bucket.s3.amazonaws.com/",
    "fields": {
      "key": "files/2a08c3d391244972a31a0f87d3821fa9/source",
      "policy": "GENERATED_POLICY",
      "x-amz-algorithm": "AWS4-HMAC-SHA256",
      "x-amz-credential": "GENERATED_CREDENTIAL_SCOPE",
      "x-amz-date": "20260921T180000Z",
      "x-amz-signature": "GENERATED_SIGNATURE",
      "x-amz-security-token": "GENERATED_SESSION_TOKEN",
      "success_action_status": "204"
    },
    "expires_at": "2026-09-21T19:00:00Z"
  },
  "id": "file_6c82bd3e319b4bb099310d54a761879e"
}
```

API v1 preview

Source: https://ottomfg.com/docs/file-object