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Introduction

StdUI is a lightweight cross-platform UI engine that can be used with any programming language. It spawns as a child process and communicates with your application via stdin/stdout using newline-delimited JSON. This allows easy integration with any language that can start a process and read/write pipes.

warning

This project is experimental. Expect bugs, missing features, and breaking changes. The API is not stable and may change without deprecation.

How it works​

Your App (Go, Python, anything)
        │  stdin  → JSON commands
        │  stdout ← JSON events
        ▼
   stdui binary (C++)
   ┌──────────────────────────────┐
   │  litehtml  — HTML/CSS layout │
   │  ImGui     — interactive     │
   │             widgets          │
   │  raylib    — window, audio   │
   └──────────────────────────────┘

StdUI uses a reduced subset of HTML/CSS (via litehtml) for layout and styling, and ImGui for interactive widgets — with no browser involved.

Features​

  • Cross-platform (Windows, macOS, Linux)
  • Language agnostic (communicates via stdin/stdout)
  • Supports a reduced subset of HTML/CSS for layout and styling
  • Pane-based layout system
  • Interactive widgets: buttons, text/number/password inputs, checkboxes, sliders, progress bars, color picker
  • Native file/folder dialogs
  • File drop support
  • Sound playback
  • Clipboard text access
  • Notification toasts
  • ~5MB binary size

Quick start​

1. Download the binary​

Grab the latest release for your platform from GitHub Releases.

Alternatively, if you are using the Go SDK, EnsureBinary can download it automatically:

if err := stdui.EnsureBinary("", ""); err != nil {
    panic(err)
}

2. Spawn and connect​

Send a settings message immediately after spawning the process:

{"action":"settings","data":{"title":"My App","windowWidth":800,"windowHeight":600}}

Wait for the ready event before sending any further commands:

{"action":"ready"}

3. Render UI​

Push HTML with update-content:

{"action":"update-content","data":"<h1>Hello!</h1><ui-button text=\"Click me\" action=\"hello\"></ui-button>"}

4. React to events​

Read stdout line by line and parse the JSON events:

{"action":"button-clicked","data":{"action":"hello","text":"Click me","pane":"main"}}

Send a new update-content whenever your state changes. There is no incremental patching — replace the whole HTML string.