curl --request GET \
  --url https://api.ledger.so/v1/users/{userId}/balance \
  --header 'Api-Key: <api-key>'

{
  "userId": "<string>",
  "creditLimit": 123,
  "pendingCharges": 123,
  "postedCharges": 123,
  "balanceDue": 123,
  "spendingPower": 123
}