A virtual machine designed for executing programs written in Hack and PHP.
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Latest commit a65cc50 Jan 16, 2017 @andrewjkennedy andrewjkennedy committed with hhvm-bot Reorder NAST definitions and functorize on annotation type
After some experimentation with the new typed AST it's become
clearer that simply embedding types directly into the AST on every
node is easier to work with than developing a fully redesigned TAST.
It should be possible simply to reuse the NAST definitions themselves,
after a little functorization. Separating off the strongly connected component
of expressions, statements, blocks, and so on makes it possible to
parameterize these types on the node annotation, instantiating with `Pos.t` for
the existing NAST and in future using `Pos.t * Typing_defs.ty option` for the

Reviewed By: hubyrod

Differential Revision: D4404007

fbshipit-source-id: f3cb5512ed4bae613649a39dffb1611de329ad11



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HHVM is an open-source virtual machine designed for executing programs written in Hack and PHP. HHVM uses a just-in-time (JIT) compilation approach to achieve superior performance while maintaining the development flexibility that PHP provides.

HHVM supports Hack, PHP 5 and the major features of PHP 7. We are aware of minor incompatibilities, so please open issues when you find them. HHVM also supports many extensions as well.

HHVM should be used together with a webserver like the built in, easy to deploy Proxygen, or a FastCGI-based webserver on top of nginx or Apache.


If you're new, try our getting started guide.

You can install a prebuilt package or compile from source.


You can run standalone programs just by passing them to hhvm: hhvm my_script.php.

If you want to host a website:

  • Install your favorite webserver. Proxygen is built in to HHVM, fast and easy to deploy.
  • Install our package
  • Start your webserver
  • Run sudo /etc/init.d/hhvm start
  • Visit your site at http://.../index.php

Our getting started guide provides a slightly more detailed introduction as well as links to more information.


We'd love to have your help in making HHVM better. If you're interested, please read our guide to contributing.


HHVM is licensed under the PHP and Zend licenses except as otherwise noted.

The Hack typechecker (hphp/hack) is licensed under the BSD license (hphp/hack/LICENSE) with an additional grant of patent rights (hphp/hack/PATENTS) except as otherwise noted.

Reporting Crashes

See Reporting Crashes for helpful tips on how to report crashes in an actionable manner.

Reporting and Fixing Security Issues

Please do not open GitHub issues or pull requests - this makes the problem immediately visible to everyone, including malicious actors. Security issues in HHVM can be safely reported via HHVM's Whitehat Bug Bounty program:


Facebook's security team will triage your report and determine whether or not is it eligible for a bounty under our program.


Our user FAQ has answers to many common questions about HHVM, from general questions to questions geared towards those that want to use.

There is also a FAQ for contributors to HHVM.