Web API performance monitor

I have a web api and I want to monitor it's performance. Let say currently it is taking 1 second to execute. Now I am doing some change in the API and want to check if the performance is same or it is taking more time. I want this whole process to automate. It should come to me as a report so that I can easily check the details. Is there any tool available or how can I do that. Please suggest some ideas.