We have three different ways to perform the 'Save' and they are listed below:
1. You can trigger the 'Save' using the
button present within the editor in the top right-corner.
2. If you have integrated our editor inside your application iframe, then you can perform the 'Save' using our postMessage Save Document API. 
As of now, this option is available only in Zoho Writer service.
3. You can also trigger the 'Save' from your application server to the Zoho server using the APIKey. When you send the API open request, we will be generating a JSON success response which consists of a 'save_url' key.
You can go ahead and use that 'save_url' to perform the 'Save' from your server to our server using the 'apikey' parameter.

How to invoke the 'save_url' from your application server?

- Get the save_url from the document open JSON response.
- Pass your apikey value inside the 'apikey' parameter.
- Method Type: POST

Please refer this link to know how the input parameters are pushed back to the user after the save is performed.