Presigned URLs | ibee | Documentation

A presigned URL is a regular HTTPS URL with an embedded signature that grants temporary access to a single object — no Access Key required by the recipient.

Use presigned URLs to:

Let a user download a private object from a browser, without giving them credentials.
Let a client upload a file directly to your bucket, bypassing your backend.
Hand a third-party system temporary access to a single file.

The URL stops working when its expiry passes.

Before you begin

A bucket (Create a bucket)
An API credential with at least Object Read & Write scope on the target bucket — used to sign URLs

The S3 endpoint for the bucket’s workspace is https://{workspaceId}.blob.ibeestorage.com.

Generate a download URL with the AWS CLI

aws --endpoint-url https://{workspaceId}.blob.ibeestorage.com \
    --profile ibee \
    s3 presign s3://my-bucket/reports/2026-05.pdf \
    --expires-in 3600

The command prints a URL with embedded signature parameters:

https://{workspaceId}.blob.ibeestorage.com/my-bucket/reports/2026-05.pdf?
  X-Amz-Algorithm=AWS4-HMAC-SHA256
  &X-Amz-Credential=...
  &X-Amz-Date=...
  &X-Amz-Expires=3600
  &X-Amz-SignedHeaders=host
  &X-Amz-Signature=...

Anyone with the URL can GET the object until the expiry passes.

Generate from an SDK

from datetime import timedelta
import boto3
s3 = boto3.client(
    "s3",
    endpoint_url="https://{workspaceId}.blob.ibeestorage.com",
    aws_access_key_id="AKIA...",
    aws_secret_access_key="<your-secret-access-key>",
)
url = s3.generate_presigned_url(
    "get_object",
    Params={"Bucket": "my-bucket", "Key": "reports/2026-05.pdf"},
    ExpiresIn=int(timedelta(hours=1).total_seconds()),
)
print(url)

Presigned uploads (`PUT`)

Generate a URL the client can PUT to directly:

url = s3.generate_presigned_url(
    "put_object",
    Params={
        "Bucket": "my-bucket",
        "Key": "uploads/avatar.png",
        "ContentType": "image/png",
    },
    ExpiresIn=600,
)

The client uploads with a single HTTP request:

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

Presigned `POST` (browser uploads with form data)

POST policies are the right fit for browser-based form uploads — they let you constrain the upload (key prefix, max size, content type) before the file is sent.

post = s3.generate_presigned_post(
    Bucket="my-bucket",
    Key="uploads/${filename}",
    Conditions=[
        ["content-length-range", 0, 10 * 1024 * 1024],   # 10 MB max
        ["starts-with", "$Content-Type", "image/"],
    ],
    ExpiresIn=600,
)
print(post)  # url + fields

Best practices

Use the shortest expiry that works. Don’t issue a long-lived URL when 5 minutes is enough.
Bind to content type and size for upload URLs to prevent abuse.
Don’t log presigned URLs — anyone who reads the log gets the same access.
Treat them as one-time secrets — regenerate per request rather than caching.

Limitations

The URL stops working if the API token used to sign it is revoked.
Each presigned URL is valid for one HTTP method on one key. Different operations need different URLs.