Surprised to see this would be in the frontpage of HN. Happy to answer any questions you may have :-)
In terms of tech stack, GFWaaS is a mix of Rails, Apache Guacamole, and headless browser. If you just want to solve your own problem, you could simply setup Guacamole on a server in China, and use VNC in your browser.
The real challenge is dealing with the Chinese Internet. For example, to get reasonable connection speed for VNC, choosing the right cloud service provider is really the key. You have to figure out a way to get an account from the major providers in China (many of them, if not all, require you either live in China or have a local entity), and test the speed and stability of the connections. And, in some cases, because of the bad traffic peering across Chinese ISPs, you website may work relatively well with one ISP but not others, so you have to test with different ISPs.
GFWaaS streamlines the whole process so you can focus on testing your website, instead of finding the right cloud service provider and setting up software etc by your own.
Hope I have explained what you asked, and sorry for my English.
The real "GFWaaS" is when you intentionally put blocked keywords on a HTTP page, triggering GFW to reset user connection. That way you can block Chinese users from accessing your website. And it's free.
My suggestion is, may be add more web browsers to your service, make it a browser compatibility test platform, and (innocently) put few servers in China. People will figure out what's going on themselves :P
"Tiananmen square massacre"
"Falun gong organ harvesting"
"Winnie the Pooh"
That's China /shrug
But the keyword is not hard to find, really ;P
It's also highly dependant on the time of day. Foreign sites are near unusable from around 7pm onwards
If I do a git push to gitlab then it can take 90 seconds to even start responding.
I hate the internet so much here that I'm never returning until the firewall is taken down. Some nights I just give up and go to bed early
I also wonder if there's really a market for such a tool? Who needs to optimize for China EVERY MONTH? Besides Cloudflare (which sucks)?
I had a similar idea of offering a service to make websites fast in China. Seems more viable.
Other than that, you're mostly fine without an ICP (Internet Content Provider) license.
One way to solve those issues could be hosting your website on a Chinese server. Note that you'll need to register with the government before you'll be allowed to do that. https://www.amazonaws.cn/en/about-aws/china/faqs/#new%20step