KRYON

The Network-Native UI Cartridge System

Define UIs in .kry • Compile to .krb • Control via CoAP

What is Kryon?

Kryon is a UI cartridge system — portable bytecode for user interfaces. Write UI definitions in a path-based VFS language, compile to portable bytecode, and control properties over the network via CoAP.

A single .krb file runs on ESP32, Plan 9, Linux, Android, and in the browser. Control your entire UI through simple file operations on network paths.

Core Features

Path-Based VFS

Every value is a file path

Portable Bytecode

Compile to .krb, run anywhere

Network-Native

Control via CoAP, HTTP, MQTT

Minimal

Under 1KB for typical UIs

Philosophy

Everything is a file — UI properties exposed as VFS paths like 0.radius, env.w
Path-based by design — All access through absolute (:sys.cons, :app.label), relative (.radius or just radius), and parent (..circle.radius) paths
Network-native by design — CoAP for lightweight, constrained-device control
Cross-platform runtime — Single .krb runs everywhere with the kray raylib renderer

Platforms

Kryon runtimes are available for multiple platforms:

Linux

Native Linux support

Plan 9

Native Plan 9 support

Android

Full runtime support

Browser

WebAssembly runtime

ESP32

Microcontroller support

Get Started

Get the Kryon compiler and runtime:

git clone https://git.sr.ht/~waozi/kryon
cd kryon
make

A simple .kry file:

. app [
    = label "hi"
    > label :sys.cons
    @ :sys.time.tick [
        ? 1000 [
            > :app.label :sys.cons
        ]
    ]
]

Compile to bytecode:

./k2b example.kry -o example.krb

Run with the renderer:

./kray example.krb

Documentation

Full documentation is available at:

README — Project overview and setup
Source Repository — Report issues and contribute