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Installation and First Run#

Get Jac installed and ready to use in under 2 minutes.

Install Jac with a single command -- no Python setup required:

curl -fsSL https://raw.githubusercontent.com/jaseci-labs/jaseci/main/scripts/install.sh | bash

This automatically installs uv (if needed), a Python 3.12+ runtime, and the full Jac ecosystem including all plugins.

Installer Options#

Pass flags after -- to customize the install:

# Core language only (no plugins)
curl -fsSL https://raw.githubusercontent.com/jaseci-labs/jaseci/main/scripts/install.sh | bash -s -- --core

# Specific version
curl -fsSL https://raw.githubusercontent.com/jaseci-labs/jaseci/main/scripts/install.sh | bash -s -- --version 2.3.1

# Standalone binary (self-contained, no Python/uv needed at runtime)
curl -fsSL https://raw.githubusercontent.com/jaseci-labs/jaseci/main/scripts/install.sh | bash -s -- --standalone

# Uninstall
curl -fsSL https://raw.githubusercontent.com/jaseci-labs/jaseci/main/scripts/install.sh | bash -s -- --uninstall
Flag Description
--core Install only the Jac language compiler, no plugins
--standalone Download a pre-built binary from GitHub Releases
--version V Install a specific version
--uninstall Remove Jac

Upgrading#

Re-run the install command to upgrade to the latest version. The installer detects existing installations and upgrades in place.

Install via pip#

If you already have Python 3.12+ and prefer pip:

pip install jaseci

The jaseci package is a meta-package that bundles all Jac ecosystem packages together. This installs:

  • jaclang - The Jac language and compiler
  • byllm - AI/LLM integration
  • jac-client - Full-stack web development
  • jac-scale - Production deployment
  • jac-super - Enhanced console output

Verify the installation:

jac --version

This also warms the cache, making subsequent commands faster.

Installation Options#

Minimal Install (Language Only)#

If you only need the core language:

pip install jaclang

Individual Plugins#

Install plugins as needed:

# AI/LLM integration
pip install byllm

# Full-stack web development
pip install jac-client

# Production deployment & scaling
pip install jac-scale

# Enhanced console output
pip install jac-super

# Create environment
python -m venv jac-env

# Activate it
source jac-env/bin/activate   # Linux/Mac
jac-env\Scripts\activate      # Windows

# Install Jac
pip install jaseci

IDE Setup#

Install the official Jac extension for the best development experience:

Option 1: From Marketplace

  1. Open VS Code
  2. Click Extensions in the sidebar (or press Ctrl+Shift+X / Cmd+Shift+X)
  3. Search for "Jac"
  4. Click Install on "Jac Language Support" by Jaseci Labs

Or install directly: Open in VS Code Marketplace

Option 2: Quick Install

Press Ctrl+P / Cmd+P and paste:

ext install jaseci-labs.jaclang-extension

Features:

  • Syntax highlighting for .jac files
  • Intelligent autocomplete
  • Real-time error detection
  • Hover documentation
  • Go to definition
  • Graph visualization

Cursor#

  1. Download the latest .vsix from GitHub releases
  2. Press Ctrl+Shift+P / Cmd+Shift+P
  3. Select "Extensions: Install from VSIX"
  4. Choose the downloaded file

Verify Installation#

jac --version

Expected output:

   _
  (_) __ _  ___     Jac Language
  | |/ _` |/ __|
  | | (_| | (__     Version:  0.X.X
 _/ |\__,_|\___|    Python 3.12.3
|__/                Platform: Linux x86_64

📚 Documentation: https://docs.jaseci.org
💬 Community:     https://discord.gg/6j3QNdtcN6
🐛 Issues:        https://github.com/Jaseci-Labs/jaseci/issues

Run your first program to confirm everything works. Create hello.jac:

with entry {
    print("Hello from Jac!");
}

jac hello.jac

You should see Hello from Jac! printed to the console.

Scaffold a Full-Stack App#

With the jac-client plugin installed, scaffold a complete full-stack project in one command:

jac create example --use fullstack
cd example
jac add
jac start main.jac

This creates a project with a Jac backend and a React frontend, ready to go at http://localhost:8000.

Community Jacpacks#

Jacpacks are ready-made Jac project templates you can spin up instantly. Since --use accepts a URL, you can run any jacpack directly from GitHub:

jac create my-todo --use https://raw.githubusercontent.com/jaseci-labs/jacpacks/main/multi-user-todo-app/multi-user-todo-app.jacpack
cd my-todo
jac add
jac start main.jac

Want to try one with AI built in? The multi-user-todo-meals-app uses Jac's AI integration features to generate smart shopping lists with costs and nutritional info. It works out of the box with an Anthropic API key:

export ANTHROPIC_API_KEY="your-key-here"
jac create meals-app --use https://raw.githubusercontent.com/jaseci-labs/jacpacks/main/multi-user-todo-meals-app/multi-user-todo-meals-app.jacpack
cd meals-app
jac add
jac start main.jac

To use any of the other jacpacks, just swap the URL:

jac create my-app --use https://raw.githubusercontent.com/jaseci-labs/jacpacks/main/<jacpack-name>/<jacpack-name>.jacpack

Upgrading Jac#

If you installed via the one-line installer, re-run it to upgrade:

curl -fsSL https://raw.githubusercontent.com/jaseci-labs/jaseci/main/scripts/install.sh | bash

If you installed via pip:

# Upgrade everything at once
pip install --upgrade jaseci

# Or upgrade individual packages
pip install --upgrade jaclang
pip install --upgrade byllm
pip install --upgrade jac-client
pip install --upgrade jac-scale
pip install --upgrade jac-super

Creating a Project#

Use jac create to scaffold a new project:

# Full-stack web app (frontend + backend)
jac create my-app --use client

# Start the development server
cd my-app
jac start main.jac

The --use client template sets up a complete project with:

  • main.jac -- Entry point with server and client code
  • jac.toml -- Project configuration
  • styles.css -- Default stylesheet
  • Bundled frontend dependencies (via Bun)

Available templates:

Template Command What It Creates
Client --use client Full-stack web app with frontend and backend
Fullstack --use fullstack Alias for --use client

You can also use community templates (Jacpacks):

jac create my-app --use <github-url>

For Contributors#

See the Contributing Guide for development setup.

Next Steps#