Tool for testing API-Interfaces

I am currently working on a project which has an API-Interface. I am now searching for a tool that can help me test the API. It would be nice if this tool can test local and public. Another point would be that the tool can run over the command line of a Linux system so that the tests can be run every hour or so.

I tested Postman which was nice, but before I pay 10$ I want to know if there are other tools. A colleague tested JMeter and found it very bad.