In Blazemeter, you can obtain your Workspace ID into a document for later use (see below screenshot). This ID (workspacesId) will be used as a parameter in the API to identify a specific workspace of your test(s) and reports(s) in Blazemeter, or any other features (Private Location, Dedicated IPs, APM, etc).
Currently, you can find the 'Workspace ID' in 2 ways,
1. In the URL line of your BlazeMeter Dashboard or Report:
Fig.2. Blazemeter Report.
2. In the Settings page, at the 'Workspaces' section (available to Admin Users):
Fig.3. Workspaces' section