The fragmentation of the LLM market has forced developers into a tedious tab-switching ritual, but a new open-source tool called Panelize aims to end that workflow. Released on October 14, 2026, Panelize is a Chrome extension that allows users to send a single prompt to up to twelve different AI providers simultaneously. By leveraging existing browser sessions rather than requiring separate API keys, it bypasses the typical configuration overhead that plagues multi-model comparison tools.

Session-Based Aggregation Over API Integration

Panelize distinguishes itself by rejecting the standard API-key architecture. Instead, it relies on the user's already-authenticated cookies for providers like ChatGPT, Claude, Gemini, Grok, and DeepSeek. This approach means there is zero setup cost for the end-user, provided they are already logged into these services in their browser. The extension supports a massive array of models, including regional giants like Doubao, Kimi, Qwen, and Zhipu, alongside Western leaders. This session-based method ensures that data stays local within the browser environment, addressing privacy concerns that often accompany third-party API aggregators.

Flexible Layouts and Prompt Management

The tool offers 22 different layout configurations, ranging from simple 1x2 comparisons to dense 1x12 grids for deep research. Users can trigger the interface via Cmd/Ctrl + Shift + E, opening a unified window that dispatches the prompt to all selected panels instantly. A built-in prompt library supports variables like {topic}, allowing for reusable templates across different providers. For developers, the project includes a robust testing suite using Playwright and Vitest, ensuring that changes in provider UIs don't break the extension's ability to interact with their composers.

Key Takeaways

  • Panelize uses existing browser sessions, eliminating the need for API keys or separate accounts.
  • It supports twelve major LLM providers, including niche Chinese models like Zhipu and Yuanbao.
  • The extension is open-source (MIT License) and prioritizes privacy by keeping data local.
  • Developers can customize layouts with 22 different grid options for various comparison needs.

The Bottom Line

Panelize is a pragmatic solution to the 'which model is best?' fatigue, proving that you don't need enterprise API access to perform serious side-by-side LLM evaluation.