Simple iframe is a tool that helps you preview any page as an iframe in the backend of TYPO3.
Keep in mind that some websites do not allow framing.
1.2.0
Download the source code either from the Git repository or from the TYPO3 Extension Repository for stable versions. Install the extension, as usual, from the Extension Manager.
The URL that you want to frame can be configured in the Extension Manager. If you need to configure the URL, switch to the module "Extension Manager", select the extension "simpleiframe" and press on the configure icon.
After configuring the URL, you can preview the framed website by clicking User Tools > Simple BE iframe.