How to Create a "Browser" in the Browser Sidebar — The Birth of Anything Copilot

In May 2022, Chrome introduced a sidebar feature supporting extensions and tool pages ¹.
We soon discovered its limitations: users might need to access ChatGPT, DeepSeek, translation tools, or multiple pages simultaneously.
This inspired us to develop an extension addressing these needs — thus Anything Copilot was born.

To display web pages in the sidebar, we had to use <iframe> since extensions lack native webview components.
Our challenge was to create a "webview-like" experience using iframes and Chrome extension APIs.

First technical hurdle: iframe limitations.
Pages can block embedding via CSP (Content Security Policy) or X-Frame-Options headers.
While restrictive, this security mechanism prevents clickjacking attacks (Clickjacking).

Our solution needed to bypass CSP/X-Frame-Options for specific iframes without compromising overall security.
The chrome.declarativeNetRequest API allowed header modification, but required precise targeting:

• tabIds: -1 restricts changes to the sidebar (not regular tabs)
• initiatorDomains limits effects to our extension's domain

This approach maintained security while enabling our core functionality.

However, sidebar implementation required rebuilding browser features:

• Multi-tab switching
• In-page search
• Zoom controls

Through iterative updates, we gradually implemented these features, evolving Anything Copilot into a powerful sidebar companion.

Real-world use cases we love:

• Playing YouTube Music in the compact sidebar during work
• Using ChatGPT/Gemini for translation when replying to store reviews

Try Anything Copilot's sidebar experience yourself: