html5ever
html5ever is an HTML parser developed as part of the Servo project.
It can parse and serialize HTML according to the WHATWG specs (aka "HTML5"). There are some omissions at present, most of which are documented in the bug tracker. html5ever passes all tokenizer tests from html5lib-tests, and most tree builder tests outside of the unimplemented features. The goal is to pass all html5lib tests, and also provide all hooks needed by a production web browser, e.g. document.write.
Note that the HTML syntax is a language almost, but not quite, entirely unlike XML. For correct parsing of XHTML, use an XML parser. (That said, many XHTML documents in the wild are serialized in an HTML-compatible form.)
html5ever is written in Rust, so it avoids the most notorious security problems from C, but has performance similar to a parser written in C. You can call html5ever as if it were a C library, without pulling in a garbage collector or other heavy runtime requirements.
Getting started in Rust
Add html5ever as a dependency in your Cargo.toml file:
[dependencies]
html5ever = "*"
Then take a look at examples/html2html.rs and examples/print-rcdom.rs and the API documentation.
Getting started in other languages
Bindings for Python and other languages are much desired.
Working on html5ever
To fetch the test suite, you need to run
git submodule update --init
Run cargo doc in the repository root to build local documentation under target/doc/.
Details
html5ever uses callbacks to manipulate the DOM, and does not provide any DOM tree representation.
html5ever exclusively uses UTF-8 to represent strings. In the future it will support other document encodings (and UCS-2 document.write) by converting input.
The code is cross-referenced with the WHATWG syntax spec, and eventually we will have a way to present code and spec side-by-side.
html5ever builds against the official stable releases of Rust, though some optimizations are only supported on nightly releases.