HEScript and Windows API together.
ExeOutput for PHP creates a single executable file: end users just need to double-click it to start the application. A main window that mimics a web browser appears and displays your PHP pages. End users browse PHP pages as if they were hosted on a remote server.
You can moreover design your own user interface style provided by your compiled application: browser style or modern Windows app. It is up to you thanks to the integrated user interface designer.
Your compiled application has three components: the internal browser, the internal storage and the PHP engine.
The internal browser lets end users navigate through your compiled website. Almost everything of the browser (interface, navigation menus, features) can be customized. The HTML rendering engine is Chromium through the use of the Chromium Embedded Framework version 3.
Console (CLI) applications do not have an internal browser: PHP works in CLI mode.
The internal storage contains source files that were compressed and encoded by ExeOutput for PHP. It also manages a virtual storage in memory where files may be unpacked to (when required). The internal storage is only accessed by the internal browser and the PHP engine.
The PHP runtime is called by the browser each time a PHP script has to be displayed. The PHP runtime interprets PHP code and generally returns HTML data that is displayed inside the browser. It retrieves all PHP files and other files from the internal storage.
All standard PHP functions may be used and you can even access remote web servers (database servers for instance) or local files. ExeOutput for PHP provides you with several functions to load and save local files:
Accessing Files in Compiled PHP Applications
How to create and save files with PHP
Advice for getting started with PHP applications in ExeOutput for PHP