Local Server Runtimes
WebToApp runs real server runtimes on-device and packages them into an installable APK. Depending on the runtime that means fork+exec of native binaries from app storage (like Termux), a JNI-embedded engine (Node.js), or a direct build-and-load driver (Go on locked-down hosts). The WebView in the generated app points at a local port served by the runtime.
Supported runtimes
| Runtime | Version | Notes |
|---|---|---|
| Node.js | 18.20.x | Runs in a dedicated :nodejs OS process via a native node_launcher wrapper loading libnode.so. Custom native .node extensions supported. |
| PHP | 8.4 | From pmmp/PHP-Binaries, downloaded once on first use. Composer 2.10.x. Custom native extensions (zend_extension, .so). |
| Python | 3.14 | Flask, Django, FastAPI (uvicorn), Tornado, built-in HTTP server. pip deps resolve into .pypackages. Versioned binary names. |
| Go | 1.26 | Official Linux arm64 toolchain (USTC mirror for CN). On-device go build / go mod / go run, vendor/ offline builds, static serving via go_exec_loader. |
| WordPress | 7.x | Over local PHP + SQLite (sqlite-database-integration). Theme and plugin import. |
A Linux Environment screen manages toolchains and dependencies for Node, PHP, Python, and Go.
How runtimes are coordinated
- Port Manager — coordinates runtime ports across generated apps via broadcast receivers, with conflict handling: reassign, auto-kill, or alert. Runtimes allocate through the Port Manager and clean up on stop.
- Local DNS bridge proxy — an HTTP CONNECT proxy in the Android JVM gives runtimes working DNS resolution and outbound HTTP where the musl/packed binary can't reach the system resolver.
- Downloads — large runtime downloads use an extended-timeout download client, not the default short-lived one.
Export requirements
When you export a runtime app, the required native libraries are embedded into the APK:
- Node.js →
libnode_bridge.so+libnode.so(16KB-aligned) +libc++_shared.so - Go →
libgo_exec_loader.so
16KB page alignment
libnode.so and other large ELF natives are 16KB-aligned for Android 15+ devices. The native launcher enables 16KB app-compat before dlopen.
Host-side preview vs generated apps
Host preview of Node.js apps goes through the same JNI launcher and works at any targetSdk. Go builds and previews in the host through a direct driver even where fork+exec is blocked. Other exec-based runtimes (PHP / Python / WordPress) can only be previewed when the host build permits exec from app storage — on the host (targetSdk ≥ 29), SELinux W^X blocks it and those previews degrade with an explicit message. Generated APKs always ship targetSdk 28 and are never affected.
Per-runtime setup guides coming soon
Detailed first-run setup, dependency installation, and troubleshooting for each runtime are being written.