Get the GUID of a document with REST

Check if this is the GUID you are looking for.

This example uses the ID property, but every fetch should work.

/sites/yourSite/_api/web/lists/getbytitle('Documents')/Items/GetById(1)?$select=id

Returned JSON (GUID is in metadata section)

{
    "odata.metadata": "https://yourServer/sites/yourSite/_api/$metadata#SP.ListData.Shared_x0020_DocumentsItems/@Element&$select=id",
    "odata.type": "SP.Data.Shared_x0020_DocumentsItem",
    "odata.id": "9b85f08e-1484-43f0-be5d-83861ca77415",
    "odata.etag": ""22"",
    "odata.editLink": "Web/Lists(guid'c8612335-fb7e-4edf-bf1d-b9186a8b987b')/Items(1)",
    "Id": 1,
    "ID": 1
}