curl --location --request GET '/rest/api/3/projectCategory'
[{"description":"First Project Category","id":"10000","name":"FIRST","self":"https://your-domain.atlassian.net/rest/api/3/projectCategory/10000"},{"description":"Second Project Category","id":"10001","name":"SECOND","self":"https://your-domain.atlassian.net/rest/api/3/projectCategory/10001"}]