CORS error on heroku app

[gregid]

Posting doesn't work:

Access to fetch at 'https://hyperapp-api.herokuapp.com/api/post' from origin 'https://hyperposts.netlify.app' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.