I wanted to call/execute the MS flow from an external application without using http request trigger. Is there a way?
I do not want to use the http trigger because the HTTP Post url cannot be called using authentication (AAD or pass bearer token).
Is there any flow api that triggers an instant flow which has authentication mechanism?
The only way to execute a flow like this with authentication that I can think of would be to use Power Apps. Users would authenticate to Power Apps and then the flow would be started by the Power Apps. But there is no way that I am aware of to do it from an external application without using an HTTP trigger.
As mentioned in my reply, you can do this using the HTTP request received trigger. Then you just need a button that does a Post to the URL defined in the trigger. The OP wanted to do it without using the http trigger. There is no way to do that.