Performance-focused replacement for Python urllib
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Latest commit fa5c05d Oct 2, 2018


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About Scurl

Scurl is a library that is meant to replace some functions in urllib, such as urlparse, urlsplit and urljoin. It is built using the Chromium url parse source, which is called GURL.

In addition, this library is built to support the Scrapy project (hence the name Scurl). Therefore, an additional function is built, which is canonicalize_url, the bottleneck function in Scrapy spiders. It uses the canonicalize function from GURL to canonicalize the path, fragment and query of the urls.

Since the library is built based on Chromium source, the performance is greatly increased. The performance of urlparse, urlsplit and urljoin is 2-3 times faster than the urllib.

At the moment, we run the tests from urllib and w3lib. Nearly all the tests from urllib have passed (we are still working on passing all the tests :) ).


We want to give special thanks to urlparse4 since this project is built based on it.

GSoC 2018

This project is built under the funding of the Google Summer of Code program 2018. More detail about the program can be found here.

The final report, which contains more detail on how this project was made can be found here.

Supported functions

Since scurl meant to replace those functions in urllib, these are supported by Scurl: urlparse, urljoin, urlsplit and canonicalize_url.


Scurl has not been deployed to pypi yet. Currently the only way to install Scurl is cloning this repository

git clone
cd scurl
pip install -r requirements.txt
make clean
make build_ext
make install

Available Make commands

Make commands create a shorter way to type commands while developing :)

make clean

This will clean the build dir and the files that are generated when running build_ext command

make test

This will run all the tests found in the /tests folder

make build_ext

This will run the command python build_ext --inplace, which builds Cython code for this project.

make sdist

This will run python sdist command on this project.

make install

This will run python install command on this project.

make develop

This will run python develop command on this project.

make perf

Run the performance tests on urlparse, urlsplit and urljoin.

make cano:

Run the performance tests on canonicalize_url.


Scurl repository has the built-in profiling tool, which you can turn on by adding this lines to the top of the *.pyx files in scurl/scurl:

# cython: profile=True

Then you can run python benchmarks/ --func [function-name] to get the cprofiling result. Currently, Scurl supports profiling urlparse, urlsplit and canonicalize.

This is not the most convenient way to profile Scurl with cprofiler, but we will come up with a way of improving this soon!

Benchmarking result report

urlparse, urlsplit and urljoin

This shows the performance difference between urlparse, urlsplit and urljoin from urllib.parse and those of Scurl (this is measured by running these functions with the urls from the file chromiumUrls.txt, which can also be found in this project):

The chromiumUrls.txt file contains ~83k urls. This measure the time it takes to run the test.

urlparse urlsplit urljoin
urllib.parse 0.52 sec 0.39 sec 1.33 sec
Scurl 0.19 sec 0.10 sec 0.17 sec

Canonicalize urls

The speed of canonicalize_url from scrapy/w3lib compared to the speed of canonicalize_url from Scurl (this is measured by running canonicalize_url with the urls from the file chromiumUrls.txt, which can also be found in this project):

This measures the speed of both functions. The test can be found in file.

scrapy/w3lib 22,757 items/sec
Scurl 46,199 items/sec


Any feedback is highly appreciated :) Please feel free to submit any error/feedback in the repository issue tab!