Automatic handling of CORS preflight requests

When creating mock APIs, chances are the front-end application and the mocked API won’t be on the same domain, thus triggering browsers OPTIONS preflight requests.

For your application to work, you can make Mockoon automatically answer to these OPTIONS requests:

Open the Environment Settings by clicking on the cog in the upper right corner:

click on cog icon

Enable the CORS option by ticking the checkbox. The option was successfully activated if a blue shield is displayed next to the environment name.

tick the CORS checkbox

You need to restart the environment for the change to take effect.

Mockoon will now automatically answer with a 200 HTTP status code to all preflight OPTIONS requests. The following headers will also be added to the response:

Access-Control-Allow-Origin: * Access-Control-Allow-Methods: GET,POST,PUT,PATCH,DELETE,HEAD,OPTIONS Access-Control-Allow-Headers: Content-Type, Origin, Accept,Authorization,Content-Length, X-Requested-With

Please note that Mockoon won’t send any CORS header on routes with the OPTIONS method (i.e. OPTIONS /my-route).

Add CORS headers to the environment headers

You can also add the same CORS headers to a mock API by clicking on the Add CORS headers to environment link:

Click on the add CORS headers link

You need to restart the environment for the change to take effect.