HTTP/1.1 302 Found Date: Fri, 26 Dec 2025 20:14:23 GMT Server: Apache Location: https://htmlpurifier.org/docs/ Content-Length: 214 Content-Type: text/html; charset=iso-8859-1 HTTP/1.1 200 OK Date: Fri, 26 Dec 2025 20:14:23 GMT Server: Apache Accept-Ranges: bytes Vary: User-Agent Last-Modified: Sun, 08 Apr 2012 05:18:50 GMT Content-Length: 5792 Content-Type: text/html

Documentation

HTML Purifier has documentation for all types of people. Here is an index of all of them.

End-user

End-user documentation that contains articles, tutorials and useful information for casual developers using HTML Purifier.

IDs

Explains various methods for allowing IDs in documents safely.

Embedding YouTube videos

Explains how to safely allow the embedding of flash from trusted sites.

Speeding up HTML Purifier

Explains how to speed up HTML Purifier through caching or inbound filtering.

UTF-8: The Secret of Character Encoding

Describes the rationale for using UTF-8, the ramifications otherwise, and how to make the switch.

Tidy

Tutorial for tweaking HTML Purifier's Tidy-like behavior.

Customize

Tutorial for customizing HTML Purifier's tag and attribute sets.

URI Filters

Tutorial for creating custom URI filters.

Development

Developer documentation detailing code issues, roadmaps and project conventions.

Implementation Progress

Tables detailing HTML element and CSS property implementation coverage.

Naming Conventions

Defines class naming conventions.

Optimization

Discusses possible methods of optimizing HTML Purifier.

Flushing the Purifier

Discusses when to flush HTML Purifier's various caches.

Advanced API

Specification for HTML Purifier's advanced API for defining custom filtering behavior.

Config Schema

Describes config schema framework in HTML Purifier.

Proposals

Proposed features, as well as the associated rambling to get a clear objective in place before attempted implementation.

Colors

Proposal to allow for color constraints.

Reference

Miscellaneous essays, research pieces and other reference type material that may not directly discuss HTML Purifier.

DevNetwork Credits

Credits and links to DevNetwork forum topics.

Internal memos

Plaintext documents that are more for use by active developers of the code. They may be upgraded to HTML files or stay as TXT scratchpads.

Type	Name	Description
End-user	Overview	High level overview of the general control flow (mostly obsolete).
End-user	Security	Common security issues that may still arise (half-baked).
Development	Config BC Breaks	Backwards-incompatible changes in HTML Purifier 4.0.0
Development	Code Quality Issues	Enumerates code quality issues and places that need to be refactored.
Proposal	Filter levels	Outlines details of projected configurable level of filtering.
Proposal	Language	Specification of I18N for error messages derived from MediaWiki (half-baked).
Proposal	New directives	Assorted configuration options that could be implemented.
Proposal	CSS extraction	Taking the inline CSS out of documents and into style.
Reference	Handling Content Model Changes	Discusses how to tidy up content model changes using custom ChildDef classes.
Reference	Proprietary tags	List of vendor-specific tags we may want to transform to W3C compliant markup.
Reference	Modularization of HTMLDefinition	Provides a high-level overview of the concepts behind HTMLModules.
Reference	WHATWG	How WHATWG plays into what we need to do.