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Lumo
Agent loop, DevTools, MCP

A calmer, more capable web.

A browser agent that acts on the page, and a userscript manager it can operate.

Explore LumoMeet UserscriptsRead the docs
Agent loopLocal-firstChrome MV3Open source
The lineup

Two precision tools for the browser you actually use.

Two products. One philosophy: local-first and calm.

Lumo

AI browser sidebar

A full agent loop with MCP browser tools, CDP DevTools and your own model.

  • Multi-step tool calling
  • DevTools, remote MCP and extension providers
  • Bring your own model
Explore Lumo

Lumo Userscripts

Userscript manager + agent endpoint

A native MV3 userscript manager with an MCP endpoint.

  • Agent endpoint with write gates and audit
  • Native chrome.userScripts and GM APIs
  • CodeMirror 6, backups and diagnostics
Explore Userscripts
The Lumo way

Craft, not chrome.

Four rules. They are the review checklist.

Read documentation
01

Invisible assistance

A good feature needs no explanatory sentence. Form and state should say what to do next.

02

Coherent familiarity

The same action feels the same everywhere. One dropdown, one dialog, one focus ring.

03

Progressive disclosure

Start with the decision. Fold the internals until someone asks for them.

04

Cinematic momentum

Motion explains cause and effect. Elements push their neighbours; nothing teleports.

Lumo

Ask. Act. Verify.

Lumo reads the page, then keeps calling tools until the job is done.

  • Multi-step loop with a visible transcript
  • DevTools, remote MCP and extension tools
  • Stop, retry and context compaction
See the agent loop
Userscripts

Scripts you can ask for.

Describe the change, approve the write, keep the audit.

  • Standard MCP over a runtime port
  • Read-only until you allow writes
  • Native chrome.userScripts
See the agent endpoint
Technical foundation

Built on primitives that last.

The products and this site share one stack.

01WXT + MV3Extension runtime
02React 19Interface
03Tailwind 4Design tokens
04Vercel AI SDKAgent loop
05MCPBrowser + agent tools
06IndexedDBLocal storage
07i18nextBilingual UI
08Cloudflare WorkersStatic delivery
MCPbrowser + agent tools
∞steps per turn
BYOKyour own provider
MV3native platform APIs
Documentation

Read the system, not just the marketing.

Agent loop, MCP, protocol, runtime and deployment.

Open the docs
npm run build
$ npm run build
✓ react-router build
✓ 30 routes pre-rendered
✓ sitemap generated
→ build/client

Static HTML, per-route metadata, zero runtime server.

Agent loopSteps, tool calls, stopping and compaction.
ConnectionsConnect from Lumo or authorize from Userscripts.
ProtocolL0 probe, L1 MCP and the security invariants.
Open the docs

Start with the browser you already use.

Install Lumo, or let it write the script that fixes your daily sites.

Install LumoGet Userscripts

A quieter, more capable web.