why POST request on POSTMAN always respond with 405?

Question

In salesforce apex, I have one custom API, It's working fine on the workbench but not work on POSTMAN, I have an access token, this works fine with GET method, but why not work with POST in POSTMAN?

APEX custom POST api is

@RestResource(urlMapping='/contactapi/*')
global with sharing class PostContactResouceWithParameter {
    @HttpPost
    global static String createNewContact(String firstName, String lastName, String birthDate, String leadSource) {
        Contact contact = new Contact();
        contact.FirstName = firstName;
        contact.LastName = lastName;
        contact.Birthdate = Date.parse(birthDate);
        contact.LeadSource = leadSource;

        //insert contact;

        return 'success';
    }
}

After POST always get 405 status.

Answer 1

I can see in image your ContactAPI c is in Caps. Also change your url to VF Domain (Classic). I can see you have lightning domain in your rest URL. If you are unsure how to get that then please use this as anonymous apex:

System.debug(Url.getOrgDomainUrl().toExternalForm() + '/services/apexrest/contactapi');

Use this api as you REST URL.