Project Structure

A typical Krema project has the following structure:

my-app/
├── krema.toml           # Krema configuration
├── pom.xml              # Maven build file
├── package.json         # Frontend dependencies
├── src/                 # Frontend source (HTML/CSS/JS)
│   ├── index.html
│   ├── main.js
│   └── style.css
├── src-java/            # Java backend source
│   └── com/example/myapp/
│       ├── Main.java    # Entry point
│       └── Commands.java # @KremaCommand methods
└── dist/                # Build output

Configuration: krema.toml

The krema.toml file is the central configuration for your Krema app:

[package]
name = "my-app"
version = "1.0.0"
identifier = "com.example.myapp"
description = "My Krema Application"

[window]
title = "My App"
width = 1200
height = 800
min_width = 800
min_height = 600
resizable = true
fullscreen = false
decorations = true

[build]
frontend_command = "npm run build"
frontend_dev_command = "npm run dev"
frontend_dev_url = "http://localhost:5173"
out_dir = "dist"

[bundle]
icon = "icons/icon.icns"
identifier = "com.example.myapp"
copyright = "Copyright 2024"

[bundle.macos]
signing_identity = ""
notarization_apple_id = ""

[permissions]
allow = [
    "fs:read",
    "clipboard:read",
    "clipboard:write",
    "notification"
]

[splash]
enabled = true
image = "splash.png"
width = 480
height = 320
show_progress = true

Window Options Reference

Option	Type	Default	Description
title	string	"Krema App"	Window title
width	int	1024	Initial width
height	int	768	Initial height
min_width	int	0	Minimum width
min_height	int	0	Minimum height
resizable	bool	true	Allow resizing
fullscreen	bool	false	Start fullscreen
decorations	bool	true	Show title bar
always_on_top	bool	false	Always on top
transparent	bool	false	Transparent background

Permissions Reference

Krema uses a permission system to control access to native APIs:

Permission	Description
fs:read	Read files from the filesystem
fs:write	Write files to the filesystem
fs:*	Full filesystem access
clipboard:read	Read from clipboard
clipboard:write	Write to clipboard
notification	Show desktop notifications
shell:execute	Execute shell commands
shell:open	Open files/URLs with default app
system-tray	System tray access
system-info	Read system information
network	Network requests
dialog	File dialogs

Frontend Directory (src/)

Contains your web UI code. Krema supports any frontend framework:

• React, Vue, Svelte, Angular
• Vanilla HTML/CSS/JS
• Any build tool (Vite, Webpack, etc.)

Java Backend (src-java/)

Contains your Java code:

• Main.java: Application entry point using Krema.app() builder
• Commands.java: Methods annotated with @KremaCommand for frontend calls
• Plugins: Custom plugin implementations

Build Output (dist/)

After running krema build:

• Compiled frontend assets
• Compiled Java classes
• Bundled JAR file
• krema-commands.d.ts — auto-generated TypeScript definitions for your @KremaCommand methods

tip

Copy krema-commands.d.ts into your src/ directory (or set -Akrema.ts.outDir to write it there automatically) to get full autocompletion and type checking for krema.invoke() calls. See TypeScript Support.

After running krema bundle:

• Platform-specific bundle (.app, .exe, .AppImage)
• Installer if configured (.dmg, .msi)