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Lumo

Lumo for Chrome

Lumo

An agent that acts inside the page.

A sidebar agent that plans, calls browser and DevTools tools, checks the result, and keeps going until the task is done.

Install from Chrome Web StoreRead the agent docs
Agent loopDevTools via CDPMCPYour own key
Agent loop

Plan. Call tools. Check. Repeat.

One turn can run as many steps as the task needs, with the whole tool chain visible and a stop button that works.

  • As many steps as the task needs
  • Parallel tool calls with typed inputs
  • Stop, retry or continue without losing state
How the loop works

One turn, many steps

model ↔ tools until the goal is met

Live

Goal + page context

Prompt, selection, tab and attachments

01

Model step

Reasoning, plan, then a tool call

02

Tool execution

MCP calls run in parallel

03

Result + next step

The loop decides again

04
Repeat until the model stops calling toolsstep 4 / ∞
No step cap by default
Stop ends the turn, not the chat
Context ring tracks the window
Compaction runs before overflow
Tool surface

Browser tools, plus DevTools.

Built-in browser tools, remote MCP, WebMCP sites and other extensions share one tool registry.

Read documentation
built-in

Browser Core

Tabs, windows, navigation, bookmarks, history, cookies, downloads.

built-in

Page Interaction

Page reading, snapshots, clicks, forms, keyboard, screenshots.

built-in

Network Monitor

Request capture, blocking, redirects and header rewriting.

CDP

DevTools Advanced

CDP sessions, trusted input, emulation and console capture.

built-in

File Manager

Read, write, patch and preview files stored locally.

remote

External MCP

HTTP Streamable or SSE, with visible status and errors.

extension

Extension MCP

Sibling extensions serve MCP over chrome.runtime.Port.

page

WebMCP

Pages declare their own tools for the active tab.

DevTools Advanced

The layer a content script cannot reach.

Trusted input, device and network emulation, console capture — through CDP.

chrome.debugger · CDP 1.3
debug_session

Attach or detach the debugger.

debug_input

Click, type, press keys and drag.

debug_emulate

Device, network, geolocation and CPU.

debug_console

Console messages and uncaught errors.

Workspace

One conversation, or three.

Run independent conversations side by side. Each pane keeps its own model, history and tool calls; drag the dividers to resize.

Lumo
Split view unlocks as the side panel widens.
Models

Your model. Your key. Three API types.

Lumo has no model of its own. Point it at Chat Completions, Responses or Anthropic Messages.

  • Chat Completions, Responses and Anthropic Messages
  • Vision, reasoning effort and context window per model
  • Keys stay local; requests go straight to your provider
Read the provider docs
Models

Three API types

One picker, one key, any compatible endpoint.

Chat Completions

The portable default for most gateways.

POST /v1/chat/completions

Responses

OpenAI's newer endpoint, with reasoning.

POST /v1/responses

Anthropic Messages

Claude models, vision and long context.

POST /v1/messages
Privacy

Your data stays on your machine.

Conversations, files and settings live in extension storage. No account, no relay.

  • No account, no telemetry
  • Files stay in IndexedDB
  • Every permission is documented
Privacy
Everything else

Built for the real web.

Quick actions

Send the page or selection from the right-click menu.

Attachments

Page, selection, image, file or pasted text.

OCR

Read images with a non-vision model.

Local files

The agent writes and previews files in IndexedDB.

Conversation history

Search and reopen past turns locally.

Chat debug

Inspect the prompt and tool calls behind a reply.

Install

Three ways in.

Store for stability, an Actions build for the newest fixes, or source.

01

Chrome Web Store

Stable and auto-updating; can lag behind main.

Open Chrome Web Store
02

GitHub Actions

Download the latest artifact, unzip, load unpacked.

Open Actions
03

Build from source

npm install, npm run build, load .output/chrome-mv3.

View source
Chromium browser with MV3 support. Firefox build from source.Privacy

Also from Lumo

Need the page rewritten?

Lumo Userscripts exposes its scripts over MCP, so the agent can write and manage them with you.

Explore Userscripts