Answer:
You can only get the number of assigned licenses using the API, the number available isn't exposed and so does not get returned.
More Information:
Given that you have licenses assigned for your domain, and the user that is querying the API has access to this information, you can retrieve the data with the following request:
curl \
'https://admin.googleapis.com/admin/reports/v1/usage/dates/2021-07-10?parameters=accounts%3Agsuite_unlimited_total_licenses&fields=*&key=[YOUR_API_KEY]' \
--header 'Authorization: Bearer [YOUR_ACCESS_TOKEN]' \
--header 'Accept: application/json' \
--compressed
While not necessary, I added the parameter field=*
in order to make sure all data is returned.
This gave me a response as such:
{
"kind": "admin#reports#usageReports",
"etag": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
"usageReports": [
{
"kind": "admin#reports#usageReport",
"date": "2021-07-10",
"etag": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
"entity": {
"type": "CUSTOMER",
"customerId": "C0136mgul"
},
"parameters": [
{
"name": "accounts:gsuite_unlimited_total_licenses",
"intValue": "233"
}
]
}
]
}
Here you can see that the intValue
for accounts:gsuite_unlimited_total_licenses
is 233 - which is reflected in the UI:

Feature Request:
You can however let Google know that this is a feature that is important for access to their APIs, and that you would like to request they implement it.
Google's Issue Tracker is a place for developers to report issues and make feature requests for their development services, I'd urge you to make a feature request there. The best component to file this under would be the Google Admin SDK component, with the Feature Request
template.