Is there a way to identify sites blocked by the website visitor's ISP?

Question

There are countries that block sites for various reasons, India being one of them. If a site is blocked by an ISP you will get a message similar to "The website has been blocked as per direction/order of Hon&rsquo;ble Court."Is there a way for me to detect this on a webpage using client side javascript or something? I am working on a site that shows all the sites that are censored/blocked by various ISP's. I can check from my ISP but want to have a site that will allow users to click a button and check sites from a predefined list to see if they are blocked or not by their ISP. The results will then be stored centrally.Tried searching the web but didn't find any usable ideas on how to achieve this, so any suggestions would be welcome.

Minor49er · Accepted Answer

You may hit some issues with CORS if you're trying to do this on a webpage that you're serving, though the ISP's interference may change this (I'm really not sure, though I wouldn't count on it).It might work better if you make a TamperMonkey script or some other client-side application that doesn't rely on a browser. In the latter case, it might even be a better idea to have small cloud-base instances set up in various regions around the globe and have them try to access sites directly where they are or use specific ISP proxies (if available) to determine access. Though that could also be a challenge.

stubez · Answer

Open Rights Group, a UK-based organisation focussed on privacy and free speech run blocked.org.uk, does something like this for UK ISPs. They provide Raspberry Pis which people run from their networks. The devices perform regular requests to various sites to check if any are blocked.