- lxml

- Developing with lxml

- Extending lxml

- Developing lxml
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# lxml - XML and HTML with Python

» lxml takes all the pain out of XML. «
Stephan Richter

lxml is the most feature-rich and easy-to-use library for processing XML and HTML in the Python language.

# Introduction

The lxml XML toolkit is a Pythonic binding for the C libraries libxml2 and libxslt. It is unique in that it combines the speed and XML feature completeness of these libraries with the simplicity of a native Python API, mostly compatible but superior to the well-known ElementTree API. The latest release works with all CPython versions from 2.4 to 3.2. See the introduction for more information about background and goals of the lxml project. Some common questions are answered in the FAQ.

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For commercial consulting, trainings and customisations, please contact Stefan Behnel.

# Documentation

The complete lxml documentation is available for download as PDF documentation. The HTML documentation from this web site is part of the normal source download.

- Tutorials:
  - the lxml.etree tutorial for XML processing
  - John Shipman's tutorial on Python XML processing with lxml
  - Fredrik Lundh's tutorial for ElementTree
- ElementTree:
  - ElementTree API
  - compatibility and differences of lxml.etree
  - ElementTree performance characteristics and comparison
- lxml.etree:
  - lxml.etree specific API documentation
  - the generated API documentation as a reference
  - parsing and validating XML
  - XPath and XSLT support
  - Python XPath extension functions for XPath and XSLT
  - custom XML element classes for custom XML APIs (see EuroPython 2008 talk)
  - a SAX compliant API for interfacing with other XML tools
  - a C-level API for interfacing with external C/Cython modules
- lxml.objectify:
  - lxml.objectify API documentation
  - a brief comparison of objectify and etree

lxml.etree follows the ElementTree API as much as possible, building it on top of the native libxml2 tree. If you are new to ElementTree, start with the lxml.etree tutorial for XML processing. See also the ElementTree compatibility overview and the ElementTree performance page comparing lxml to the original ElementTree and cElementTree implementations.

Right after the lxml.etree tutorial for XML processing and the ElementTree documentation, the next place to look is the lxml.etree specific API documentation. It describes how lxml extends the ElementTree API to expose libxml2 and libxslt specific XML functionality, such as XPath, Relax NG, XML Schema, XSLT, and c14n. Python code can be called from XPath expressions and XSLT stylesheets through the use of XPath extension functions. lxml also offers a SAX compliant API, that works with the SAX support in the standard library.

There is a separate module lxml.objectify that implements a data-binding API on top of lxml.etree. See the objectify and etree FAQ entry for a comparison.

In addition to the ElementTree API, lxml also features a sophisticated API for custom XML element classes. This is a simple way to write arbitrary XML driven APIs on top of lxml. lxml.etree also has a C-level API that can be used to efficiently extend lxml.etree in external C modules, including fast custom element class support.

# Download

The best way to download lxml is to visit lxml at the Python Package Index (PyPI). It has the source that compiles on various platforms. The source distribution is signed with this key. Binary builds for MS Windows usually become available through PyPI a few days after a source release. If you can't wait, consider trying a less recent release version first.

The latest version is lxml 2.3.2, released 2011-11-11 (changes for 2.3.2). Older versions are listed below.

Please take a look at the installation instructions!

This complete web site (including the generated API documentation) is part of the source distribution, so if you want to download the documentation for offline use, take the source archive and copy the `doc/html` directory out of the source tree.

It's also possible to check out the latest development version of lxml from github directly, using a command like this (assuming you use hg and have hg-git installed):

    hg clone https://github.com/lxml/lxml.git lxml

You can also browse the source repository and its history through the web. Please read how to build lxml from source first. The latest CHANGES of the developer version are also accessible. You can check there if a bug you found has been fixed or a feature you want has been implemented in the latest trunk version.

# Mailing list

Questions? Suggestions? Code to contribute? We have a mailing list.

You can search the archive with Gmane or Google.

# Bug tracker

lxml uses the launchpad bug tracker. If you are sure you found a bug in lxml, please file a bug report there. If you are not sure whether some unexpected behaviour of lxml is a bug or not, please check the documentation and ask on the mailing list first. Do not forget to search the archive (e.g. with Gmane)!

# License

The lxml library is shipped under a BSD license. libxml2 and libxslt2 itself are shipped under the MIT license. There should therefore be no obstacle to using lxml in your codebase.

# Old Versions

See the web sites of lxml 1.3, 2.0, 2.1, 2.2 and the latest in-development version

- lxml 2.3.1, released 2011-09-25 (changes for 2.3.1)
- lxml 2.3, released 2011-02-06 (changes for 2.3)
- lxml 2.3beta1, released 2010-09-06 (changes for 2.3beta1)
- lxml 2.3alpha2, released 2010-07-24 (changes for 2.3alpha2)
- lxml 2.3alpha1, released 2010-06-19 (changes for 2.3alpha1)
- lxml 2.2.8, released 2010-09-02 (changes for 2.2.8)
- lxml 2.2.7, released 2010-07-24 (changes for 2.2.7)
- lxml 2.2.6, released 2010-03-02 (changes for 2.2.6)
- lxml 2.2.5, released 2010-02-28 (changes for 2.2.5)
- lxml 2.2.4, released 2009-11-11 (changes for 2.2.4)
- lxml 2.2.3, released 2009-10-30 (changes for 2.2.3)
- lxml 2.2.2, released 2009-06-21 (changes for 2.2.2)
- lxml 2.2.1, released 2009-06-02 (changes for 2.2.1)
- lxml 2.2, released 2009-03-21 (changes for 2.2)
- older releases