cloudflare down

What is Cloudflare? Why did the Cloudflare outage take down nearly half the world's internet?
some parts of the web appear to be down due to technical issues at cloudflare.
Cloudflare has a problem, a series of large websites are not accessible
the world famous intermediary dns service, cloudflare has just encountered a problem, causing cloudflare.com homepage and a series of websites using the company's services to meet 502 bad gateway error and cannot be accessed.