Sign file URL

Creates a signed URL that grants temporary access to a fal CDN file, regardless of its ACL. Useful for sharing access-restricted files.

The signature is valid for expiration_seconds (up to 7 days).

Authentication: Required. The API key must have the assets:read permission.

POST /storage/files/sign

Sign file URL

cURL

curl --request POST \
  --url https://api.fal.ai/v1/storage/files/sign \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "expiration_seconds": 3600
}
'

import requests

url = "https://api.fal.ai/v1/storage/files/sign"

payload = { "expiration_seconds": 3600 }
headers = {
    "Authorization": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({expiration_seconds: 3600})
};

fetch('https://api.fal.ai/v1/storage/files/sign', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

200

{
  "signed_url": "https://v3.fal.media/files/b/0a1b2c3d/output.png?identity=..."
}

{
  "error": {
    "type": "validation_error",
    "message": "Invalid request parameters"
  }
}

{
  "error": {
    "type": "authorization_error",
    "message": "Authentication required"
  }
}

{
  "error": {
    "type": "authorization_error",
    "message": "Access denied"
  }
}

{
  "error": {
    "type": "not_found",
    "message": "Resource not found"
  }
}

{
  "error": {
    "type": "rate_limited",
    "message": "Rate limit exceeded"
  }
}

{
  "error": {
    "type": "server_error",
    "message": "An unexpected error occurred"
  }
}

Authorizations

Authorization · string · header · required

API key must be prefixed with "Key ", e.g. Authorization: Key YOUR_API_KEY

Query Parameters

url · string<uri> · required

Full URL of the fal CDN file, as returned by the upload APIs (https://v3.fal.media/files/b//). Must not contain query parameters.

Example:

"https://v3.fal.media/files/b/0a1b2c3d/output.png"

Body

application/json

Signing options for the file URL

expiration_seconds · integer · required

How long the signed URL stays valid, in seconds (max 7 days)

Required range: 1 <= x <= 604800

Example:

3600

Response

200

application/json

Signed URL granting temporary access

Signed URL response

signed_url · string · required

URL with an embedded signature granting temporary access

Example:

"https://v3.fal.media/files/b/0a1b2c3d/output.png?identity=..."