WebBrain

Open-source AI browser agent for chatting with pages, automating tasks, and running multi-step workflows with your choice of LLM.

English · 中文 · Français · Docs · Website · MIT License

WebBrain is a browser extension that puts an AI agent in a side panel next to your tabs. Ask it about the page you're on, or hand it a task and let it click, type, and navigate its way through. It runs on the model you choose — a local llama.cpp or Ollama server, a frontier cloud API, or the managed default that needs no setup at all.

Install

Install from the Chrome Web Store, Firefox Add-ons, or Edge Add-ons.

Or load it from source

git clone https://github.com/webbrain-one/webbrain.git

Chrome — open chrome://extensions/, enable Developer mode (top right), click Load unpacked, and select the webbrain/src/chrome folder.

Firefox — open about:debugging#/runtime/this-firefox, click Load Temporary Add-on, and select src/firefox/manifest.json. Temporary add-ons are removed when Firefox restarts; permanent installation requires signing via addons.mozilla.org.

Use it

Click the WebBrain icon to open the side panel, then type something like:

• "Summarize this page"
• "Find all links about pricing"
• "Fill in the search box with 'AI agents' and click Search"
• "Navigate to github.com and find trending repositories"

Three modes control what the agent is allowed to do:

Mode	What it can do
Ask	Read-only. Reads the page, answers questions, fetches URLs.
Act	Clicks, types, navigates, uploads, downloads, fills forms.
Dev	Adds page source, styles, console, network, and reversible page edits.

Pick a model

WebBrain Cloud 1.0 is the default and needs no API key or local setup.

Local models need no API key either. Point WebBrain at any OpenAI-compatible server:

llama-server -m your-model.gguf --port 8080          # llama.cpp
ollama serve                                          # Ollama  → :11434/v1
vllm serve your-model --port 8000                     # vLLM    → :8000/v1
python -m sglang.launch_server --model-path your-model --port 30000

LM Studio (:1234/v1), Jan (:1337/v1), and LocalAI (:8080/v1) work the same way. Load a model with at least a 16k-token context window — 8k works only with the Compact tier, and 4k is too small for the system prompt plus tool schemas. WebBrain auto-detects the real window for llama.cpp, Ollama, and LM Studio, and auto-compacts the conversation as it fills up. There is also a preview ollama launch webbrain --model <model> handoff. Details: providers and models.

Cloud APIs — OpenAI, Anthropic Claude, Google Gemini, Azure OpenAI, AWS Bedrock, Mistral, DeepSeek, xAI Grok, MiniMax, Kimi, Qwen, z.ai GLM, Groq, Together, Cloudflare, Nvidia NIM, Hugging Face, Fireworks, OpenRouter, and more. Settings ships 103 built-in provider cards with base URLs and default models pre-filled — see the full catalog.

Features

• Reads any page — text, links, forms, tables, PDFs, and interactive elements, via the accessibility tree rather than brittle selectors
• Acts on it — click, type, scroll, navigate, upload, download, and verify forms, with per-site permission prompts before consequential actions
• Plan before Act — Act and Dev can generate a structured plan, show it for approval, and pin the approved plan to the scratchpad before any tool runs
• Multi-step agent — autonomous tool-use loop, configurable up to 195 steps (default 130), with a Continue button when it hits the limit
• Saved workflows — turn a successful run into a reusable, value-free workflow you can re-run, export, and share
• Scheduled tasks and watches — /schedule for later, /watch to poll a page and act when a condition is met
• Skills — trusted instructions and tools that load only when relevant
• Smart context — token-aware auto-compaction, tool-result limits, and emergency overflow recovery
• Per-tab conversations — each tab keeps its own history; optional local user memory for stated preferences
• Reading-first side panel — streaming Ask replies, floating controls that keep your question in view as answers grow, copy buttons, a page-inspection banner, and a stop button that works mid-run
• Deterministic by default — temperature 0.15 for browser-control decisions, 0.3 for Ask, 0 for vision screenshot descriptions

Agent tools

WebBrain separates tier from mode. Tier (compact, mid, full) is a per-provider setting controlling how many tools a model sees — Compact suits small local models, Full unlocks hover, drag-drop, frames, and shadow DOM. Mode (ask, act, dev) controls what the user is allowing.

The full tool-by-tier matrix, WebMCP notes, and Dev-mode diagnostics are in agent tools.

Slash commands

Type /help in the panel for full signatures and flags. The most useful ones:

Command	What it does
/ask · /act · /dev · /plan	Switch mode before sending
/schedule [prompt]	Create a scheduled task
/watch [--keep] [--secs <30-120>] [--long | --short] <condition and action> [/beep]	Poll the current page and act when a condition is met
/workflow --save <name>	Compile the last successful run into a reusable workflow
/memory --add <text>	Save a user preference
/screenshot [--full-page]	Capture the tab, or the full scrollable page
/record [--transcribe]	Record the current tab, optionally saving a transcript
/export [--traces | --config]	Download the conversation, tool chain, or a Settings snapshot
/compact · /reset · /verbose	Compact context, clear the conversation, toggle tool detail
/allow-api	Per-conversation override letting fetch_url mutate when the UI is failing

/watch runs its first check immediately, then polls every 60 seconds (--secs accepts 30–120). Relative conditions like "when a new commit appears" establish a baseline on the first check; --keep keeps the watch running and suppresses repeated alerts for the same stable event key.

Full reference, including /dangerously-skip-permissions and the run-capture suffixes: slash commands.

Keyboard Shortcuts

Chrome side panel shortcuts work when the WebBrain side panel has focus.

Shortcut	What it does
Ctrl+/ or Cmd+/	Focus the input
Ctrl+Shift+A or Cmd+Shift+A	Switch to Ask mode
Ctrl+Shift+X or Cmd+Shift+X	Switch to Act mode
Ctrl+Shift+D or Cmd+Shift+D	Switch to Dev mode
Escape	Stop the active run, unless it is only dismissing slash-command autocomplete
Escape twice	Stop an active recording from WebBrain or browser pages

Documentation

Architecture	System overview, turn flow, subsystems
Agent tools	Tiers, modes, and the full tool matrix
Slash commands	Every command and flag
Providers and models	All 103 provider cards, local setup, tiers
Skills	Bundled skills, importing, skill tools
Security model	Permissions, credentials, trust boundaries
Prompt-injection defense	Defense layers and known gaps
Privacy and data flow	What leaves the browser, and what doesn't
Accessibility tree and refs	How pages are read and targeted
Site adapters	Per-site guidance
Export and workflow formats	webbrain-config/1, webbrain-workflow/1
Adding a tool · Localization · Test scenarios	Contributor guides

Also available in 中文 and Français.

Repository layout

src/chrome/     Manifest V3 build — service worker, chrome.scripting, sidePanel
src/firefox/    Manifest V2 build — background page, executeScript, sidebar_action
docs/           Design and reference docs (en, zh-CN, fr)
lmstudio-plugin/  fetch_url + research_url as a standalone LM Studio plugin
web/            Landing site and docs site
test/           Node test suite, LLM scenario benchmarks, security corpora

Nearly all agent code is shared between the two builds. See architecture for where they diverge.

Known issues

Firefox is meaningfully weaker than Chrome. Firefox has no equivalent to the Chrome DevTools Protocol via chrome.debugger, so the Firefox build has no shadow-DOM piercing, no real trusted mouse events (some React/Vue handlers won't fire), no closed-shadow-root traversal, no resolveSelector retry budget, no SPA-navigation-aware retry, and no CDP screenshots (it falls back to tabs.captureVisibleTab, active tabs only). Site adapters, vision detection, loop detection, the auto-screenshot loop, and the Compact prompt/tool set are mirrored to Firefox. Some single-page apps may also fail to trigger content-script re-injection after client-side navigation.

Contributing

See CONTRIBUTING.md. To add a tool, follow the checklist in adding a tool. To add a provider, subclass BaseLLMProvider, implement chat() (and optionally chatStream()), and register it in providers/manager.js — mirroring both changes to src/chrome/ and src/firefox/. All providers normalize to { content, toolCalls, usage }; details in providers and models.

Recent changes are in CHANGELOG.md.

LM Studio plugin

fetch_url and research_url also ship as a standalone LM Studio plugin at webbrain/web-tools, for web-fetching tool-use inside LM Studio chats without the browser extension. Pure Node, no headless browser.

lms clone webbrain/web-tools

Source: lmstudio-plugin/.

Star History

Contributors

Citation

@software{webbrain2026,
  author = {Sokullu, Emre},
  title = {WebBrain: Open-source AI browser agent for chatting with pages},
  year = {2026},
  publisher = {GitHub},
  url = {https://github.com/webbrain-one/webbrain}
}

License

MIT — built by Emre Sokullu