How to get all configured Jira fields via REST call
The easiest way to get all fields configured and available in Jira is by requesting a REST call in a browser.
Steps:
Open your Jira in a web browser (Firefox, Mozilla etc.)
Log in
Open a new browser tab
In the new tab enter the URL https://*#PUT_HERE_YOUR_JIRA_NAME#*.atlassian.net/rest/api/3/field ( Do not forget to replace the *#PUT_HERE_YOUR_JIRA_NAME#* with the name of your Jira instance)
After clicking Enter, you should see the following screen:
Right click in the browser search field and choose Save Page As / Save As to store the data as a JSON file on your computer.