GetStatusCode.com/521 will always return a 521 HTTP Status Code. That is by design.
This status code is not specified in any RFCs, but is used by CloudFlare's reverse proxies to indicate that the origin webserver refused the connection.
For easy reference, some of the details of your request have been included below.
This is a tool that I built just to give me an easy way to test scripts that need to handle a variety of http status codes. Even if I'm not integrating with a REST API or other web service that might present a variety of status codes, I often still need to gracefully handle the occasional unexpected 500 error. Short of deliberately coding a glitch (which is only an option if I'm in control of the remote end, which isn't always the case), it's hard to test this. So, I wrote this handy site that responds with the appropriate header for the major codes.
Whether you want to test code like I often do or just see an example 521 http status code, this is a handy tool to use. Plus, it offers some basic information that I occasionally need as well, like IP geolocation (and it even uses HTML5 geolocation to tell how far off they are from each other) and user agent parsing for browser and operating system.
This tool is free to use, but you should be mindful of its limitations. It does not fully and properly implement the HTTP specification (it's not RESTful in the slightest). It only spits out this page (roughly, with some variation by code requested) and the associated HTTP status code headers. My scripts key off those response headers (as do most frameworks I've dealt with), so that's sufficient to test. But if you're expecting a 301 to actually include a Location header, you won't find it here.
If you appreciate this tool, feel free to link to it, share it on Facebook, and the like. The more people use this, the more I can justify adding features.
|Ashburn||VA||US||301 Moved Permanently|
|Ashburn||VA||US||505 HTTP Version Not Supported|
|Ashburn||VA||US||494 Request Header Too Large (Nginx)|
|Ashburn||VA||US||406 Not Acceptable|
|Ashburn||VA||US||598 Network read timeout error (Unknown)|