10 Key Facts About OpenGravity: The Zero-Install Vanilla JS IDE Clone

OpenGravity is a bold new open-source IDE that clones Antigravity’s interface while adding its own twist—zero dependencies, no build steps, and a bring-your-own-key (BYOK) model. Created by a high school student juggling GCSEs, this project emerged from frustration with Antigravity’s usage limits and random errors. The result? A lightweight, vanilla JavaScript environment powered by WebContainer API and xterm.js. Here are ten essential facts you need to know about this intriguing tool.

1. The Problem That Sparked OpenGravity

The creator relied heavily on Google Antigravity for side projects but hit frequent usage caps and encountered “agent terminated” errors. These disruptions made development unreliable. Rather than accept the limitations, they decided to build their own version—one that would offer similar functionality without the restrictions. OpenGravity was born from a practical need: a free, self-hosted IDE that respects user control and avoids arbitrary cutoffs. This hands-on approach also taught the developer valuable lessons about API integration and UI cloning.

2. Faithful UI Clone

Loving Antigravity’s clean and intuitive interface, the developer replicated it as accurately as possible. Every visual element—from the layout to the color scheme—mirrors the original. However, some UI elements like dropdowns and buttons are currently hardcoded placeholders due to the short development timeline (just a few days before exams). The team plans to refine them later, but the core aesthetic remains intact, offering a familiar workspace for users switching from Antigravity.

3. Pure Vanilla JavaScript—No Frameworks

In a world dominated by React, Vue, and build tools, OpenGravity stands out by using only plain HTML, CSS, and JavaScript. This decision keeps the codebase extremely lightweight: no npm install, no webpack, no transpilation. The entire IDE runs directly in the browser, making it easy to fork, modify, and host anywhere. It’s a refreshingly simple foundation that encourages contributions without requiring a complex development environment.

4. Real Terminal via WebContainer API and xterm.js

Instead of simulating a terminal, OpenGravity integrates the WebContainer API to provide a genuine Linux environment inside the browser. This allows the AI agent to execute shell commands, install dependencies, and edit files exactly as if running on a remote server. Combined with xterm.js for terminal rendering, the experience feels native. The integration was notoriously difficult to get right, but the effort pays off: users can now run real development workflows without any backend infrastructure.

5. BYOK (Bring Your Own Key) for Total Privacy

OpenGravity adopts a BYOK model: users input their own API key (Gemini, OpenAI, etc.), which stays exclusively in localStorage. No keys are sent to the server, ensuring complete control and privacy. This approach eliminates dependency on a central service and avoids subscription fees. It also aligns with the project’s open-source ethos—transparency in how your data is handled. The only catch? You need to provide your own key to unlock the agent’s capabilities.

6. Alpha Stage with Active Development

Currently labeled as alpha, OpenGravity works but has rough edges. The AI can start projects, edit files, and run commands, but many UI elements are placeholders. The core logic is solid, but features like complex agent workflows or polished buttons are still to come. The developer admits building it in a few days pre-exams, so stability may vary. Early adopters should expect occasional glitches, but the foundation is strong enough to build upon.

7. Early Open Source Release

The developer chose to release OpenGravity open source now, despite its alpha state, to let the community experiment while they focus on exams. This decision underscores a belief that a vanilla JS + WebContainer IDE has immense potential. By sharing the code early, they hope others will contribute features impossible in closed-source tools—like custom agent loops or collaborative editing. The GitHub repo is live, and issues/pull requests are welcome.

8. How to Get Started

Visit the live demo at opengravity.pages.dev (zoom to 80% if not full screen). On load, the app asks for a Gemini API key (store in localStorage). After that, upload a folder to start working. You can then use the terminal and AI agent to run commands, edit files, or kickstart a project. The process is straightforward: no signup, no backend setup. Just a browser and a key.

9. Built for Custom Agent Workflows

OpenGravity’s architecture is designed to support complex custom agent workflows that proprietary tools cannot. Because the entire codebase is vanilla JS and open source, developers can integrate specialized agents, modify the terminal behavior, or even hook into other APIs. The WebContainer API enables real-time file system changes, making it suitable for auto-testing, code generation, or prototyping. This flexibility is a key differentiator from locked-down IDEs.

10. The Future: Community-Driven Evolution

The long-term vision for OpenGravity relies on community contributions. The foundation—vanilla JS, WebContainer, BYOK—is minimal but extensible. Contributors can fix placeholder UI, improve the agent loop (e.g., better error handling, streaming responses), or add features like multi-file editing and version control. The developer hopes that during their exam period, others will take the reins and push the project forward. It’s a call for collaboration on a tool built by a student for everyone.

Conclusion: OpenGravity exemplifies how frustration with limitations can spark a creative, open-source solution. Despite its alpha status, it already provides a functional, privacy-respecting IDE alternative. Whether you’re a curious developer or a potential contributor, this project offers a unique sandbox to explore vanilla JS, WebContainer, and community-driven development. Try it out, share feedback, and help shape its evolution.