Kandelo: a multi-process POSIX WASM kernel running WordPress entirely in the browser

Kandelo is an open-source kernel based on WebAssembly that emulates a multi-process POSIX environment in the browser and in Node.js—enough to run WordPress server-side, without a server.

The concrete case

Imagine deploying WordPress in a browser tab, with no server, no container, no backend at all. This is one of the use cases that Kandelo is actively exploring—replacing WordPress Playground, their previous foundation, with this new WASM kernel.

Why it exists

Kandelo is an open-source, POSIX-compatible, multi-process kernel based on WebAssembly (WASM). It runs in modern browsers and in Node.js. Its goal: to enable existing software—written for Linux, POSIX, or classic environments—to run in a browser sandbox with minimal changes.

This is a WASM promise we’ve been hearing for years, but few projects have pushed it as far in terms of multi-process support. Most WASM runtimes bundle a single binary; Kandelo manages multiple processes that communicate with each other—a real kernel, not just a container.

Under the hood

• POSIX compatibility: a wide range of existing software can run with little to no recompilation
• Multi-process: real management of multiple processes running in parallel inside the browser sandbox
• Targets: modern browsers + Node.js
• Status: experimental but already functional across a broad spectrum of software

The technical 'why'

WASM provides a secure, portable sandbox. Adding a POSIX kernel layer on top opens the door to an entire class of applications (web servers, shell scripts, CLI tools) that were not previously feasible inside the browser. WordPress Playground is the most concrete demonstration of this.

# Kandelo’s principle in one line of thought:
# Linux app → compiled to WASM → runs in Kandelo kernel → in your browser

Key takeaway: Kandelo doesn’t compile a specific program to WASM—it runs a full POSIX kernel in WASM, allowing existing code to execute inside it.

Project to watch: kandelo.dev – open source, experimental, contributions welcome.