Swagger Editor is a web application and by it's nature is limited to HTTP access control policy. If you can't make calls using Try this operation component of the editor it's very likely because the server is not allowing swagger.io domain make XHR (also known as AJAX) calls to it.
There are multiple ways of fixing the CORS issue in Swagger Editor. You can modify your server if you own it or run Swagger Editor in an environment that ignores HTTP access control policy.
To enable CORS in your server you need to add following headers to your HTTP responses
Access-Control-Allow-Origin: http://swagger.io
Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept
Note that Access-Control-Allow-Origin accepts a regular expression. You can put * for it's value to allow CORS calls from any domain(origin).
If you don't want to add CORS headers to your server, the other option is to host Swagger Editor in your own domain. When Swagger Editor is running in the same domain as the API it's editing, it can makes calls to your domain with no restriction. Run the following commands to generate a new build of Swagger Editor and serve the dist folder statically in your domain.
When an XHR call is not cross-domain, JavaScript will see all the headers. If you want to see more accurate response, this method is preferred.
git clone https://github.com/swagger-api/swagger-editor.git
cd swagger-editor
npm run build
# now dist folder have a fresh build of Swagger Editor
You can make calls using a proxy to enable CORS for your API. Many API management providers provide proxies for enabling CORS. You can also run your own proxy. For example you can use cors-it proxy if you're using Node.js.
Browsers have HTTP access control enabled by default but you can disable it in the setting.
To run Chrome with HTTP access control disabled use --disable-web-security flag.
For example in OSX you need to run the following command:
/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --disable-web-security