401 Unauthorized during Sketch API resource access

Question

When integrating with the Sketch REST API, authentication is managed via an API token passed in the Authorization header. While requests missing a token consistently return a 401 Unauthorized response, there is uncertainty regarding the API's behavior when a token is syntactically valid but lacks the necessary permissions for a specific resource.

The goal is to distinguish between a complete authentication failure and a scoped permission deficiency during integration testing in a development workspace.

Does the Sketch API return a 401 Unauthorized or a 403 Forbidden when a valid token lacks specific resource permissions?
  Is the error payload consistent across different endpoints when encountering these permission-based failures?

Tasadduq Burney · Answer

Authentication vs. Authorization in Sketch API
In the Sketch REST API, a 401 Unauthorized response specifically indicates an authentication failure. This means the server cannot verify the identity of the requester because the token is missing, malformed, expired, or revoked. If a token is syntactically valid and successfully identifies the user, but that user lacks the necessary permissions to access a specific resource, the API typically returns a 403 Forbidden response.

Likely Behavior and Implementation Logic
While standard REST patterns dictate the 401/403 split, integration testing should account for the following behavioral nuances:

401 Unauthorized: Triggered when the Authorization header is missing, the Bearer prefix is omitted, or the token has been invalidated.
  403 Forbidden: Triggered when the token is valid, but the account associated with that token does not have the required workspace role or resource-level access to perform the requested action.

Verification Steps for Integration Testing
To distinguish between these two states in a development workspace, execute the following sequence of requests:

Baseline Validation: Call a low-privilege endpoint (such as a profile or "me" endpoint). If this returns a 401, the token itself is invalid.
  Permission Testing: Use the same token to access a restricted resource. A transition from a 200 (on the profile endpoint) to a 403 (on the resource endpoint) confirms a scoped permission deficiency.
  Negative Testing: Send a request with a randomly generated string as the token. This should consistently return a 401.

Scoped Command for Verification
Use cURL to verify the response code for a specific resource:
curl -i -H "Authorization: Bearer YOUR_TOKEN" https://api.sketch.tools/v1/resource_endpoint

Diagnostic Requirement
To provide a more definitive answer regarding payload consistency, please specify the API version and the specific resource type (e.g., Workspace, Document, or User) you are targeting, as error schemas can vary between legacy and current endpoints.

401 Unauthorized during Sketch API resource access

1 answer

Authentication vs. Authorization in Sketch API

Likely Behavior and Implementation Logic

Verification Steps for Integration Testing

Scoped Command for Verification

Diagnostic Requirement

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Infrastructure Verification Checklist