SOAPUI is the best interface to make tests to JIRA Web Services. And it’s free.
It’s very easy, only install and make the test.
Set the Endpoint to your JIRA URL Domain and protocol (http or https) and put the resource URL to the REST Endpoint (like /rest/api/2/PROJECT-NUM/worklog to put worklog in an issue as example).
Set the method “POST” ( or PUT or DELETE )
And select the text type “application/json” and add “started” (date to put the worklog) “timeSpent” (the hours to log)
In the Headers of the request set “Basic user:password encrypted in base64 (all user:password)”
Run the request and measure the response time ( in the lowest part of the window of the request)