Sending POST parameters with Postman doesn't work, but sending GET parameters does

I faced the same issue in PostMan and Advance REST Client both. I checked through fiddler and found that my request payload is not converted into JSON format.

I am passing my data in Body as x-www-form-urlencoded

You can fix it by using Content-Type as application/x-www-form-urlencoded in request header.

I was setting the url in Postman to be http:// but Apache was redirecting to https:// and somehow the POST variables were being dropped along the way.

After I changed it to https://, the POST variables worked properly.

See also: https://stackoverflow.com/a/28461500/704803

Simply use the Body Tab and enter the post parameters there. Note that Body Tab is disabled if Get is selected.