how browsers transform URLs

Erik van der Poel erikv at
Wed Nov 25 20:49:36 CET 2009

We are happy to announce the open source release of Client URL
Internet Emission Sniffer (CURLIES).

The purpose of this project is to see how browsers and other Web
clients transform URLs as they access them. This is done by generating
a number of test cases and having each client load the test files
while running a packet sniffer to capture the network emissions.
Reports are then generated from the sniffed packets, highlighting
differences between the clients. For further details and test results,
see the project site:

I have also written some recommendations for browser developers. While
the HTML5 Web Addresses spec already describes how to parse and
resolve a URL, I have taken this a step further to include the DOM
interfaces that can be used to obtain IRIs, URIs and Unicode host

Happy Thanksgiving!


PS Many thanks to Shaopeng Jia (Google), who did most of the actual work.

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