patchbay : patchbay.pub is a free web service you can use to implement things like static site hosting, file sharing, cross-platform notifications, webhooks hand...
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Yellow Lab Tools : Online test to help speeding up heavy web pages
HTTP Archive : The HTTP Archive tracks how the Web is built.
Mockbin : Mockbin allows you to generate custom endpoints to test, mock, and track HTTP requests & responses between libraries, sockets and APIs.
Differentiate HTTP headers and content body of two GET URLs.