WebextLLM

WebextLLM was created as the first extension to embed large language models inside the browser itself. Rather than forwarding your text to a cloud endpoint, it ships the models with the extension and runs them in an isolated environment, so the only thing needed to start chatting is the browser you already have. That design removes configuration, accounts and API keys from the setup entirely.

The extension doubles as an app platform. Through the window.ai interface, websites and other extensions can request access to the locally hosted model, letting developers build AI features on top of a runtime that lives in the browser. A permission layer shows you which applications are asking for access and lets you grant or deny it, alongside a history of the prompts and responses exchanged with your model.

Because the model runs on your hardware, WebextLLM is free to use, private and effectively unlimited, and it keeps functioning without an internet connection. The developer is candid that it is an experimental proof-of-concept rather than a production tool, and warns that risks such as data loss or system issues are assumed by the user. It is best treated as a hands-on way to explore browser-native AI and the emerging window.ai ecosystem.