Append the option and corresponding value to your URL in your browser's address bar. You may find the [Firefox UrlParams extension](https://addons.mozilla.org/en-US/firefox/addon/1290) useful in order to debug a POST requests (Like Forms).
| flush=1 | | 1 | | Clears out all caches. Used mainly during development, e.g. when adding new classes or templates. Requires "dev" mode or ADMIN login |
| showtemplate | | 1 | | Show the compiled version of all the templates used, including line numbers. Good when you have a syntax error in a template. Cannot be used on a Live site without **isDev**. |
| isDev | | 1 | | Put the site into [development mode](../), enabling debugging messages to the browser on a live server. For security, you'll be asked to log in with an administrator log-in. Will persist for the current browser session. |
| debug_request | | 1 | | Show all steps of the request from initial [HTTPRequest](api:SilverStripe\Control\HTTPRequest) to [Controller](api:SilverStripe\Control\Controller) to Template Rendering |