Cappuccino is an open-source framework that supports building powerful, desktop-class applications running in any modern web browser. Instead of direct manipulation of HTML, CSS, and the DOM, applications are built using Objective-J, a superset of JavaScript modeled on Objective-C.
Cappuccino faithfully implements the proven design patterns of NeXTSTEP/Apple's Cocoa frameworks, enabling the creation of incredibly complex and reliable applications with a fraction of the code.
✨ Project Status: Active Development & Node.js Transition Cappuccino has been under continuous development since 2008 and is actively maintained. A major transition to a modern, Node.js-based toolchain has recently been finalized. The current release is a production-ready Release Candidate, with a formal release scheduled for 2025. It is stable, fast, and ready for new projects.
Cappuccino is not intended for building simple websites. It is for building applications—especially complex, data-rich, line-of-business tools where productivity and user experience are paramount.
- 💻 True Desktop Behavior, Out-of-the-Box: Applications built with Cappuccino behave like native desktop software by default. This includes a rich palette of UI controls, full keyboard navigation and focus management, and multi-level undo/redo support — all implemented without requiring a single extra line of code. See the Kitchen Sink demo.
- 🚀 Incredible Productivity: Less code is needed. High-level abstractions and a powerful object-oriented model mean development is focused on application logic, not browser quirks.
- 🏛️ Stable & Mature: Built on decades of proven API design from Cocoa®, Cappuccino provides a stable foundation, free from the churn common in the JavaScript ecosystem.
- 🧱 True Object-Oriented Architecture: Objective-J's message-passing architecture promotes loose coupling and clean design, making large-scale applications easier to build and maintain.
- 🌐 Platform Independent: Development can be done on macOS, Windows, or Linux. Deployment can target any modern web browser.
A new Cappuccino application can be running in five minutes.
Node.js (LTS versions are recommended) and npm are required.
To avoid potential permission issues with global packages, setting a local directory for npm is the recommended approach.
# Tell npm where to install global packages
npm set prefix ~/.npm
# Add this directory to the shell's path in .zshrc, .bash_profile, etc.
export PATH="~/.npm/bin:$PATH"The shell must be restarted or the profile sourced (source ~/.zshrc) for the changes to take effect. For more details, see the npm documentation.
npm install -g @objj/cappuccino# 1. A new project is generated
capp gen HelloWorld
# 2. Move into the new directory
cd HelloWorld
# 3. A local web server is started (Python 3 example)
python3 -m http.server 8000
# 4. The new app can be opened in any modern browser
# http://localhost:8000A fully-functional Cappuccino application has now been created.
Objective-J is a strict superset of JavaScript, which means all JavaScript code is valid Objective-J code. It adds the powerful object-oriented features of Smalltalk and Objective-C, like explicit message-passing and class-based inheritance.
The syntax might look different, but it is designed for clarity and power.
- Objective-C:
NSString *greeting = [NSString stringWithFormat:@"Hello, %@!", name];
- Objective-J:
var greeting = [CPString stringWithFormat:@"Hello, %@!", name];
Pure JavaScript and Objective-J can be mixed and matched, even in the same file. The Objective-J code is transpiled into highly-optimized JavaScript for deployment, but can also be run directly in the browser during development.
- Official Website: cappuccino.dev
- Documentation & Tutorials: cappuccino.dev/learn/, cappuccino cookbook
- Gitter Community Chat: gitter.im/cappuccino/cappuccino
- GitHub Wiki: github.com/cappuccino/cappuccino/wiki
- FAQ: cappuccino.dev/support/faq.html
- Report a Bug: Create a GitHub Issue
Q: What are the advantages over React or Vue?
A: React and Vue are excellent libraries for building web UIs. Cappuccino is a comprehensive framework for building entire applications. It provides a fully integrated stack—including a mature UI library, event handling, and data management—designed for large-scale development.
Beyond this, Cappuccino provides a more integrated and powerful data-binding layer inspired directly by Cocoa, which dramatically reduces boilerplate code for complex UIs:
- Sophisticated Data Bindings: Going beyond simple state-to-view mapping, Cappuccino's binding technology, based on Key-Value Coding (KVC), allows data models to be declaratively linked directly to UI components.
- Powerful Controller Layer: Dedicated controller objects (like
CPArrayController) are used to mediate between data and views. These controllers automatically handle sorting, filtering, and selection state, completely decoupling the UI from the business logic. - Advanced Filtering with Predicates: A table displaying thousands of items can be filtered simply by setting a predicate (a declarative filter rule, e.g.,
lastName BEGINSWITH 'S') on its controller. The UI updates instantly. This eliminates tons of manual state management and filtering logic code. - Automatic Value Transformation: Data can be easily formatted for display (e.g., dates, currency, booleans to "Yes/No") directly within the binding itself using value transformers, keeping model data pure and view logic minimal.
Q: Can Cappuccino be used on Windows/Linux?
A: Yes. The development tools run on Node.js and are platform-independent. Applications can be developed on any OS and deployed on any web server.
Q: Is Xcode required?
A: No. Any code editor can be used. Xcode offers optional visual development tools for macOS users, but it is not a requirement.
Q: Hasn't Apple moved on from Objective-C, making these APIs obsolete?
A: While Swift is Apple's newer language, Objective-C and AppKit remain foundational, actively supported technologies used in many of Apple's flagship applications. Cappuccino leverages the stability and power of this time-tested API design, which is independent of Apple's future product roadmap.
Q: How can custom HTML, CSS, or JavaScript libraries be integrated?
A: Cappuccino abstracts away the DOM, but other web technologies can still be integrated. The CPWebView control allows arbitrary HTML/CSS/JS content to be embedded. Since Objective-J is a superset of JavaScript, JS libraries can be used and JS functions can be called directly from Objective-J code.
Q: Does the LGPL license permit closed-source commercial applications?
A: Yes. The LGPLv2 license allows proprietary, closed-source applications to be built and distributed using Cappuccino. Sharing of source code is only required for any modifications made to the Cappuccino framework itself. The application code remains proprietary.
To contribute to Cappuccino or to use the absolute latest, un-released changes, the project can be built from source.
git clone https://github.com/cappuccino/cappuccino.gitcd cappuccinonpm install(This bootstraps the build process using the latest release)jake buildjake dist(This will install the locally-built toolchain, potentially overwriting your npm version)
To switch back to the official release, npm install -g @objj/cappuccino can be run again.
Cappuccino is released under the GNU Lesser General Public License (LGPL) version 2.1 (or later).
This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
Cocoa® is a registered trademark of Apple Inc.