Uploads and URL inputs

Every generation input is an asset in your organization’s Library before a model sees it, so ZeroGen can check its real type and duration, which pricing depends on. You can give an input in either of two ways:

Asset ID. Upload the file first, then send its asset ID. Uploads take images, video, and audio of up to 5 GiB.
URL. Send an https URL, and ZeroGen imports it into your Library before it quotes the request. URLs take smaller images and video.

{
  "model": "openai/gpt-image-2/edit",
  "prompt": "Turn the sky into a sunset",
  "inputs": [
    { "role": "source", "asset": "9e8d7c6b-5a4f-4e3d-8c2b-1a0f9e8d7c6b" },
    { "role": "reference", "url": "https://example.com/sunset-palette.png" }
  ]
}

Each input has a role and exactly one of asset or url. The model’s request schema lists the roles it takes and the media each accepts; for details, see Models.

Upload a file

Uploading takes three requests. Each needs the uploads:create scope.

Start the upload

Send the file’s name, media type, and size to POST /v1/uploads:

curl https://api.zerogen.com/v1/uploads \
  -H "Authorization: Bearer $ZEROGEN_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: 8a7b6c5d-4e3f-4a2b-9c1d-0e9f8a7b6c5d" \
  -d '{
    "filename": "storyboard.png",
    "contentType": "image/png",
    "sizeBytes": 2483011,
    "sha256": "3a5f0c1e9b7d2a4c6e8f0b1d3a5c7e9f1b3d5a7c9e1f3b5d7a9c1e3f5b7d9a1c"
  }'

Field	Description
`filename`	Required. The file’s name.
`contentType`	Required. The file’s media type, from the list in Supported files.
`sizeBytes`	Required. The file’s exact size in bytes, up to 5 GiB.
`sha256`	Optional. The file’s SHA-256 digest in lowercase hex. With it, an identical file already in the project is reused.
`projectId`	Optional. The project to upload into. Defaults to your organization’s default project.
`folderId`	Optional. A folder in that project to add the asset to.

The response is 201 with status: "upload_required", an upload target, and a Location header for the upload:

{
  "id": "6d5c4b3a-2f1e-4d0c-9b8a-7f6e5d4c3b2a",
  "projectId": "5a4b3c2d-1e0f-4a9b-8c7d-6e5f4a3b2c1d",
  "status": "upload_required",
  "assetId": null,
  "upload": {
    "method": "PUT",
    "url": "https://storage.example.com/...",
    "headers": { "Content-Type": "image/png" },
    "expiresAt": "2026-10-21T17:19:05.000Z"
  }
}

If you sent sha256 and the project already has an identical file, the response is 200 with status: "ready" and that file’s assetId, and you can skip the next two steps.

Send the bytes

PUT the file’s exact bytes to upload.url with every header in upload.headers, before expiresAt. The target is valid for 15 minutes. Don’t send your API key to it.

curl -X PUT "$UPLOAD_URL" \
  -H "Content-Type: image/png" \
  --data-binary @storyboard.png

Complete the upload

Complete the upload by its id, with no request body:

curl -X POST https://api.zerogen.com/v1/uploads/6d5c4b3a-2f1e-4d0c-9b8a-7f6e5d4c3b2a/complete \
  -H "Authorization: Bearer $ZEROGEN_API_KEY"

ZeroGen verifies the stored file and returns status: "ready" with the assetId to send as an input. If the project already has an identical file, assetId is that file’s. Completing again returns the same asset.

GET /v1/uploads/{id} returns an upload as it stands, without its upload target. You can read only uploads you started. When you name a folderId, a ready response from POST /v1/uploads or POST /v1/uploads/{id}/complete carries a folder object that reports whether the asset was filed there: filed is true or false, and error explains a refusal. An upload_required response has no folder object yet. The asset stays usable either way.

Use a URL as an input

Send url in place of asset:

{ "role": "reference", "url": "https://example.com/sunset-palette.png" }

ZeroGen’s servers download the URL, check the file, and save it to your Library as an ordinary upload in the generation’s project, before quoting the request. The model provider never receives your URL, and ZeroGen doesn’t store it, so you can send a signed URL. Importing the same file again reuses its asset, and an imported asset stays in your Library until someone deletes it. A URL input has these limits:

The URL uses https on port 443 and a domain name, and is at most 2,048 characters long.
The file is a PNG, JPEG, or WebP image of up to 50 MiB, or an MP4 or MOV video of up to 100 MiB. ZeroGen checks the type from the file’s bytes, not from its name or headers.
Each download must finish within 30 seconds.
Audio inputs can’t be URLs. Upload audio first.

ZeroGen imports a request’s URLs one at a time, and downloads a URL repeated across inputs once. Quotes import URL inputs too. A request with a URL input needs the uploads:create scope in addition to generations:create. Without it, the request fails with 403 permission_denied before ZeroGen downloads anything. If ZeroGen can’t use a URL, the request fails with 400 input_import_failed, param names the input, such as inputs[1].url, and nothing is charged. The error doesn’t say whether a host exists or refused the connection. Your organization’s URL imports also have rate limits.

Supported files

Uploads accept the following media types:

Kind	Media types
Image	`image/png`, `image/jpeg`, `image/webp`, `image/gif`, `image/avif`, `image/bmp`, `image/tiff`
Video	`video/mp4`, `video/quicktime`, `video/webm`, `video/x-matroska`, `video/x-msvideo`
Audio	`audio/mpeg`, `audio/wav`, `audio/aac`, `audio/mp4`, `audio/ogg`, `audio/flac`, `audio/aiff`

Each model accepts a subset. Its request schema’s x-roles lists the media types for each role, and urlAccept lists the ones a URL input can be.

Test keys

A test key uploads and imports only into its API sandbox project. A projectId for any other project returns 404 not_found.

Get started

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Conventions

Uploads and URL inputs

Upload a file

Use a URL as an input

Supported files

Test keys

​Upload a file

​Use a URL as an input

​Supported files

​Test keys

Upload a file

Use a URL as an input

Supported files

Test keys