See the API's various operations for details on their request parameters and response data:

OperationMethodEndpoint
Accounts
List accountsGET/accounts-with-categories
Categories
Get a categoryGET/categories/​{categoryId}
Cases
List casesGET/cases
Create a new casePOST/cases
Get a caseGET/cases/​{caseId}
Update a casePATCH/cases/​{caseId}
Close a casePOST/cases/​{caseId}/​request-case-closure
List commentsGET/cases/​{caseId}/​comments
Comment a casePOST/cases/​{caseId}/​comments
List attached filesGET/cases/​{caseId}/​attachments
Attach a filePOST/cases/​{caseId}/​attachments
Get an attached fileGET/cases/​{caseId}/​attachments/​{attachmentId}
Get the status of an attachment uploadGET/cases/​{caseId}/​attachments/status/{uploadId}