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 tab at the top of the window:

click on the settings tab

Enable the **Automatically handle OPTIONS pre-flight requests ** by ticking the checkbox:

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 all routes of a mock API with one click.

Open the Environment Headers by clicking on the tab at the top of the window:

click on the headers tab

Then, click on the Add CORS headers link:

Click on the add CORS headers link

The above headers will be automatically added to your list of headers:

view cors headers in the list