Neon API (unofficial showcase)
POST/projects/{project_id}/branches/{branch_id}/buckets/{bucket_name}/objects/{object_key}/presign

Presign an upload or download for an object in a bucket

Returns a presigned URL that transfers bytes directly to or from the object's bucket on the specified branch, without the caller ever handling S3 credentials. The operation field selects the direction:

  • upload returns a presigned PUT URL (the caller PUTs the file bytes straight to url with the returned headers). Authorized with project write access.
  • download returns a presigned GET URL (the caller GETs the bytes straight from url). Authorized with project read access.

The platform mints a short-lived credential and builds the SigV4-signed URL against the branch's S3 data-plane host, returning it together with the HTTP method, any headers the caller must echo, and the URL's expiry.

Served by the user's session (no customer S3 credentials required).

Note: This endpoint is currently in Beta.

  • IdempotentThe SDK sends Idempotency-Key, so a retried request is only applied once.

4 parameters · 3 body fields
project_idstringrequired
The Neon project ID
branch_idstringrequired
The Neon branch ID
bucket_namestringrequired
The bucket name
object_keystringrequired
The object key. Keys may contain `/`; the `/` characters of nested keys must be percent-encoded (`%2F`) in the path segment.
operationstringrequired
The transfer direction. `upload` returns a presigned `PUT` URL; `download` returns a presigned `GET` URL.
Allowed:uploaddownload
content_typestringoptional
The `Content-Type` to bind into the signed request. Only meaningful for `upload`: when set, the caller MUST send the same `Content-Type` header on the `PUT`, and the value is echoed back in the response `headers`. Ignored for `download`.
expires_in_secondsintegeroptional
How long the presigned URL stays valid, in seconds. Defaults to 900 (15 minutes); capped at 604800 (7 days).
Default:900

3 status codes
200A presigned URL valid until `expires_at`. The caller transfers the object bytes by issuing `method url` with the returned `headers`.
urlstringrequired
The presigned URL. Transfer the object bytes by issuing `method url` with the returned `headers`.
methodstringrequired
The HTTP method to use against `url`: `PUT` for an upload, `GET` for a download.
headersobjectrequired
Headers the caller MUST send verbatim on the request (e.g. `Content-Type` when it was signed on an upload). May be empty.
expires_atstringrequired
When the presigned URL stops being valid.
404Bucket or branch not found
request_idstringoptional
Unique identifier for the request, useful for debugging. You can set this value manually by including an `X-Request-ID` header in the request. If not provided, the value will be generated automatically.
codestringrequired
Machine-readable code classifying the error type. See `message` for a human-readable explanation.
Default:
messagestringrequired
Error message
defaultGeneral Error. The request may or may not be safe to retry, depending on the HTTP method, response status code, and whether a response was received. - If no response is returned from the API, a network error or timeout likely occurred. - In some cases, the request may have reached the server and been successfully processed, but the response failed to reach the client. As a result, retrying non-idempotent requests can lead to unintended results. The following HTTP methods are considered non-idempotent: `POST`, `PATCH`, `DELETE`, and `PUT`. Retrying these methods is generally **not safe**. The following methods are considered idempotent: `GET`, `HEAD`, and `OPTIONS`. Retrying these methods is **safe** in the event of a network error or timeout. Any request that returns a `503 Service Unavailable` response is always safe to retry. Any request that returns a `423 Locked` response is safe to retry. `423 Locked` indicates that the resource is temporarily locked, for example, due to another operation in progress.
request_idstringoptional
Unique identifier for the request, useful for debugging. You can set this value manually by including an `X-Request-ID` header in the request. If not provided, the value will be generated automatically.
codestringrequired
Machine-readable code classifying the error type. See `message` for a human-readable explanation.
Default:
messagestringrequired
Error message

Error handling

A 404 is returned: Bucket or branch not found. Any other status is an error: General Error.

The request may or may not be safe to retry, depending on the HTTP method, response status code, and whether a response was received.

  • If no response is returned from the API, a network error or timeout likely occurred.
  • In some cases, the request may have reached the server and been successfully processed, but the response failed to reach the client. As a result, retrying non-idempotent requests can lead to unintended results.

The following HTTP methods are considered non-idempotent: POST, PATCH, DELETE, and PUT. Retrying these methods is generally not safe. The following methods are considered idempotent: GET, HEAD, and OPTIONS. Retrying these methods is safe in the event of a network error or timeout.

Any request that returns a 503 Service Unavailable response is always safe to retry.

Any request that returns a 423 Locked response is safe to retry. 423 Locked indicates that the resource is temporarily locked, for example, due to another operation in progress.