webbrain-one/webbrain

What WebBrain does

WebBrain is a Chrome, Firefox, and Edge extension that adds an AI agent side panel next to the tabs. It reads the current page through the accessibility tree, answers questions about it, and can click, type, scroll, navigate, upload, download, and fill forms when permitted. It is aimed at people who want to query pages or hand repetitive browser work to an agent while staying in the browser session they are already logged into.

The model is pluggable. The managed default, WebBrain Compass 1.0, needs no API key. Local servers such as llama.cpp, Ollama, vLLM, LM Studio, and Jan are supported through OpenAI-compatible endpoints, and a large catalog of cloud providers is available on the Providers page.

Install and first run

1. Install the extension from the Chrome Web Store, Firefox Add-ons, or Edge Add-ons. To load it from source instead, clone the repository, and for Chrome open chrome://extensions/, enable Developer mode, click Load unpacked, and select src/chrome; a cleaned copy from npm run build:chrome sits in build/chrome. Firefox loads the manifest via about:debugging#/runtime/this-firefox; temporary add-ons disappear when Firefox restarts.
2. Click the WebBrain icon to open the side panel and send a message such as "Summarize this page" to use the read-only Ask mode.
3. To let the agent interact with the page, switch to Act with /act or write an instruction that clearly asks for browser actions; consequential actions trigger per-site permission prompts. Dev adds source, styles, console, and network access for development work.
4. To use a local model, start an OpenAI-compatible server (for example ollama serve on port 11434) and select the matching provider, or use the WebBrain Companion desktop app on http://127.0.0.1:8327/v1; see the provider setup guide.

Operating modes and tools

The README separates tier (compact, mid, full) from mode (ask, act, dev): the tier controls how many tools a model sees, while the mode controls what it is allowed to do. Compact is intended for small local models; Full unlocks hover, drag-and-drop, frames, and shadow DOM. Vision mode lets an image-capable model work from screenshots and coordinates. Act and Dev can generate a plan for approval before any tool runs. The tool matrix is documented in agent tools.

Slash commands cover scheduling (/schedule), page watching (/watch), saved workflows, memory, screenshots, recording, and context compaction. /help in the panel lists all signatures and flags; full syntax is in the slash commands reference.

Constraints and known limitations

Firefox is explicitly described as weaker than Chrome. Without Chrome DevTools Protocol access, the Firefox build lacks shadow-DOM piercing, trusted mouse events, closed-shadow-root traversal, CDP screenshots, and some SPA navigation handling, and some React or Vue event handlers may not fire. Local models need enough context window for prompts, tool schemas, page content, and history; 16k is a fallback, not a guaranteed minimum.

For local and bring-your-own providers, the Share queries for research switch is off by default. Turning it on shares a bounded, content-free diagnostic timeline plus scrubbed prompt and response data for that provider; disabling it purges queued diagnostics. The security model and privacy and data flow documents describe permission and data boundaries. The project is licensed GPL-3.0-or-later because the distributed extension bundles the GPL-licensed Xapian/libzim WebAssembly runtime.

Related components

A separate MCP server (@webbrain/mcp-server) lets coding agents such as Claude Code, Codex, Cursor, and OpenClaw delegate tasks to the browser session the user is already signed into. It exposes task-level tools rather than raw browser primitives so that the in-browser permission gate stays in the agent loop. An LM Studio plugin (webbrain/web-tools) provides the same delegation plus plain HTTP tools that work without a browser. The extension holds only one bridge socket at a time, so WebBrain Cloud, the MCP server, and the LM Studio plugin must be selected one at a time under Settings → Bridge.

HotRepo's take

WebBrain recorded a best position of 3 on the JavaScript daily list on 2026-11-03 with 26 stars gained that day, but no all-language daily rank is known. That is a single snapshot, so it supports the fact of a strong one-day JavaScript ranking, not a trend. The notable technical detail for readers is the broad provider matrix and the explicit Chrome-over-Firefox tradeoff; neither is evidence of adoption or reliability.