I have a community user who needs to hit a chatter rest api endpoint. Is there any way to test if the user can hit the api.
It is a community user so i cannot use workbench.
You don't need workbench to access any REST API endpoints. What you need is:
As long as you have the pre-requisite, any User set in Salesforce will be able to access REST API endpoints.
I presume that you are attempting to test the connection to the Chatter API REST Endpoint. You could use the following tools to verify your connection and get a sense of the expected request and the JSON response returned.