HtmlSave.com was first released on 22-June-2019 from the official website. We could find the oldest archive of this website from the Wayback archive machine from here.
From about 4-February-2020 it started using HtmlSave.net for hosting user-hosted content in the subdomains.
HtmlSave is a website which can help you to host single HTML codes online anonymously for free even without the need of a registration purpose.
But later, due to increasing phishing content, users need to register an account using Google to use the service.
In fact the service quiet helpful for absolute beginners who just need to host a single HTML file online and want to see how it actually look in a browser online.