OPTIONS method is used to return the other methods supported by the server-side at the given URL. By default in GNU Artanis, for a specified URL, every method whose handler was registerted would be added to its own OPTIONS list.
If you want to deny certain methods for security consideration, you may need to set server.allowedmethods in config.
NOTE: If you’re not trying to use Cross-Origin Resource Sharing (CORS), then you may not need to care about it.