Title: Compiling PHP Published: July 15, 2026 Last modified: July 16, 2026 --- # Compiling PHP ## In this article * [Building](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#building) * [PHP next builds](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#php-next-builds) * [PHP extensions](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#php-extensions) * [C API exposed to JavaScript](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#c-api-exposed-to-javascript) * [Build configuration](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#build-configuration) [ Back to top](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#wp--skip-link--target) The build pipeline lives in a [`Dockerfile`](https://github.com/WordPress/wordpress-playground/blob/trunk/src/packages/php-wasm/compile/Dockerfile). It was originally forked from [seanmorris/php-wasm](https://github.com/seanmorris/php-wasm) In broad strokes, that `Dockerfile`: * Installs all the necessary linux packages (like `build-essential`) * Downloads PHP and the required libraries, e.g. `sqlite3`. * Applies a few patches. * Compiles everything using [Emscripten](https://emscripten.org/), a drop-in replacement for the C compiler. * Compiles `php_wasm.c` – a convenient API for JavaScript. * Outputs a `php.wasm` file and one or more JavaScript loaders, depending on the configuration. * Transforms the Emscripten’s default `php.js` output into an ESM module with additional features. To find out more about each step, refer directly to the [Dockerfile](https://github.com/WordPress/wordpress-playground/blob/trunk/src/packages/php-wasm/compile/Dockerfile). ### 󠀁[Building](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#building)󠁿 To build all PHP versions, run `nx recompile-php:all php-wasm-web` (or `php-wasm- node`) in the repository root. You’ll find the output files in `packages/php-wasm/ php-web/public`. To build a specific version, run `nx recompile-php:all php-wasm- node --PHP_VERSION=8.0 --WITH_JSPI=yes` (and repeat with `--WITH_JSPI=no`). ### 󠀁[PHP next builds](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#php-next-builds)󠁿 Playground can also run the next PHP version from the php-src development branch in the web runtime. These builds are published separately from the main repository because the generated WebAssembly files are large and change often. The nightly refresh workflow builds the php-src development branch, writes the web artifacts to the gitignored `packages/playground/website/public/php-next/` directory, and publishes the result to the `php-next-builds` branch. Website deploys and the local dev server sync that branch before serving `?php=next`. To refresh the local copy manually, run: ```language-sh npm run sync:php-next ``` To rebuild the web artifacts locally from the php-src development branch, run: ```language-sh npm run recompile:php:web:next ``` `php=next` currently ships web main modules only. Matching extension side modules and Playground CLI support are separate follow-up work. ### 󠀁[PHP extensions](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#php-extensions)󠁿 PHP is built with several extensions listed in the [`Dockerfile`](https://github.com/WordPress/wordpress-playground/blob/trunk/src/packages/php-wasm/compile/Dockerfile). Some extensions, like `zip`, can be turned on or off during the build. Others, like` sqlite3`, are hardcoded. If you need to turn off one of the hardcoded extensions, feel free to open an issue in this repo. Better yet, this project needs contributors. You are more than welcome to open a PR and author the change you need. PHP.wasm can also load dynamic `.so` extensions before PHP starts. Built-in dynamic extensions such as `intl`, `xdebug`, `redis`, and `memcached` are distributed with the Node package, and external extensions can be supplied with a manifest that selects the artifact matching the active PHP version and async mode. See [Loading PHP extensions](https://developer.wordpress.org/playground/developers/apis/javascript-api/php-extensions) for the runtime API. ### 󠀁[C API exposed to JavaScript](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#c-api-exposed-to-javascript)󠁿 The C API exposed to JavaScript lives in the [`php_wasm.c`](https://github.com/WordPress/wordpress-playground/blob/trunk/src/packages/php-wasm/compile/build-assets/php_wasm.c) file. The most important functions are: * `void phpwasm_init()` – It creates a new PHP context and must be called before running any PHP code. * `int phpwasm_run(char *code)` – Runs a PHP script and writes the output to /tmp/ stdout and /tmp/stderr. Returns the exit code. * `void phpwasm_refresh()` – Destroy the current PHP context and starts a new one. Call it after running one PHP script and before running another. Refer to the inline documentation in [`php_wasm.c`](https://github.com/WordPress/wordpress-playground/blob/trunk/src/packages/php-wasm/compile/build-assets/php_wasm.c) to learn more. ### 󠀁[Build configuration](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#build-configuration)󠁿 The build is configurable via the [Docker `--build-arg` feature](https://docs.docker.com/engine/reference/commandline/build/#set-build-time-variables---build-arg). You can set them up through the `build.js` script, just run this command to get the usage message: ```language-sh nx recompile-php php-wasm-web ``` **Supported build options:** * `PHP_VERSION` – The PHP version to build, default: `8.0.24`. This value must point to an existing branch of the https://github.com/php/php-src.git repository when prefixed with `PHP-`. For example, `7.4.0` is valid because the branch ` PHP-7.4.0` exists, but just `7` is invalid because there’s no branch `PHP-7`. The PHP versions that are known to work are `7.4.*` and `8.0.*`. Others likely work as well but they haven’t been tried. * `EMSCRIPTEN_ENVIRONMENT` – `web` or `node`, default: `web`. The platform to build for. When building for `web`, two JavaScript loaders will be created: `php-web. js` and `php-webworker.js`. When building for Node.js, only one loader called` php-node.js` will be created. * `WITH_LIBXML` – `yes` or `no`, default: `no`. Whether to build with `libxml2` and the `dom`, `xml`, and `simplexml` PHP extensions (`DOMDocument`, `SimpleXML`,..). * `WITH_LIBZIP` – `yes` or `no`, default: `yes`. Whether to build with `zlib`, ` libzip`, and the `zip` PHP extension (`ZipArchive`). * `WITH_NODEFS` – `yes` or `no`, default: `no`. Whether to include [the Emscripten’s NODEFS JavaScript library](https://emscripten.org/docs/api_reference/Filesystem-API.html#filesystem-api-nodefs). It’s useful for loading files and mounting directories from the local filesystem when running php.wasm from Node.js. First published July 15, 2026 Last updated July 16, 2026 Edit article [ Improve it on GitHub: Compiling PHP ](https://raw.githubusercontent.com/WordPress/wordpress-playground/trunk/packages/docs/site/docs/developers/23-architecture/03-wasm-php-compiling.md) Changelog [ See list of changes: Compiling PHP ](https://developer.wordpress.org/playground/developers/architecture/wasm-php-compiling/?output_format=md#) [ Previous: WebAssembly PHP](https://developer.wordpress.org/playground/developers/architecture/wasm-php-overview/) [ Next: PHP.js JavaScript module](https://developer.wordpress.org/playground/developers/architecture/wasm-php-javascript-module/)