axuse — browser & computer use, done right

Accessibility-first browser and computer use for agent harnesses. One MCP server plugs into Codex, Claude Code, OpenCode, Antigravity, or any MCP-capable host. Zero dependencies (Node ≥ 22). Windows desktop driver is verified; macOS desktop control is available as an explicit opt-in with native TCC permission checks; Linux desktop control runs over X11/XWayland (XTEST input + capture + EWMH windows, zero extra packages).

The design is distilled from the two best implementations of this problem — OpenAI's Codex Chrome extension and the ZCode harness — and exists to prove a point: a screenshot loop is not the right interface for a machine. The DOM tree, the accessibility tree, and CDP are. axuse instruments the target instead of photographing it.

Not a developer? You don't need anything below. In the Claude desktop app, download axuse.mcpb from ax-use.com and double-click it. In ChatGPT's Codex app, Claude Code, Cursor or any other agent, paste the install prompt and the agent sets axuse up for you. See the non-developer guide.

Proven in production

axuse is maintained by CTOL Digital Solutions (ctol.digital), a leading AI, Strategy and IT consultancy. This work has been tested and used at large scale across many client engagements. CTOL Digital Solutions holds the copyright of all the code.

Quick start

You need Node.js 22+ and a Chromium-family browser (Chrome, Edge, Chromium, or Chrome for Testing; found automatically, or set AXUSE_BROWSER=/path/to/chrome). On a bare server with no browser and no sudo: node src/cli.js install-browser provisions a pinned Chrome for Testing under ~/.cache/axuse — nothing else: axuse has no npm dependencies.

1. Get it and check the environment

git clone https://github.com/ctoldigital/axuse.git
cd axuse
node src/cli.js doctor        # finds a browser, launches it, takes a snapshot

For a daily Chrome/Edge session, use the guided bridge setup. It registers the native host, opens the extensions page, prints the exact folder to load, and can print your harness configuration in the same command:

node src/cli.js setup --browser chrome --harness codex

After clicking Load unpacked once, verify the connection with:

node src/cli.js bridge verify

2. Add it to your harness (use your absolute path to src/cli.js)

# Codex
codex mcp add axuse -- node /abs/path/axuse/src/cli.js mcp

# Claude Code
claude mcp add --scope user axuse -- node /abs/path/axuse/src/cli.js mcp

# OpenCode, Antigravity, any other MCP host: print the config block to paste
node src/cli.js print-config --harness opencode   # or agy | generic

3. Ask for something in the browser

Open https://example.com, find the "More information" link and tell me where it goes.

The agent calls ax_open, reads the accessibility snapshot, and acts on element refs like [ref=e7]. Each action returns only what changed.

Optional settings (environment variables for the MCP server)

To drive your own logged-in Chrome instead of a fresh browser, see Driving your daily browser.

Servers, no desktop (Ubuntu server lane)

axuse runs under agent CLIs (codex, claude code, opencode) on headless Ubuntu servers. Challenge/anti-bot pages check is this a headless browser? first, so server mode never uses --headless: it boots a private Xvfb and runs Chrome fully headed on it — real headed build, no headless fingerprint (verified live against Turnstile: ax_solve_captcha solves on a server with no desktop, and the slider engine's human-curve drags land 10/10). Beyond headed-vs-headless, server mode covers persona coherence (AXUSE_TIMEZONE/AXUSE_LANG matching the egress persona, AXUSE_DISPLAY_SIZE=random fleet diversity, --disable-blink-features= AutomationControlled so navigator.webdriver stays false at the source) and fleet hygiene (zombie-Xvfb sweep). Solver plugins that need vision call a multimodal model through any OpenAI-compatible API; keys come from env vars or an owner-only secrets file. One-time setup, systemd wiring, env reference and scale notes: docs/server-mode.md — and node src/cli.js doctor verifies the whole lane (it prints the measured anti-bot posture and persona).

Benchmark

On 16 server-scored browser tasks, run in the same harness (Codex CLI) with the same model against Codex's own Chrome extension and browser-use 0.13:

Accuracy tied on those tasks. A harder 7-task extension (checkout flow, virtualized grid, date pickers, signup errors, nested iframes, file upload, local dev app) has been run once so far: axuse 7/7; Codex + Chrome failed 2 by stopping to ask for confirmation; browser-use failed 1. Method, anti-cheat rules and how to reproduce: bench/suite/README.md. Install footprint and setup comparison: bench/suite/EASE.md.

Why this is faster and more reliable than screenshot CUA

Install into a harness

node src/cli.js print-config --harness codex       # or claude-code | opencode | agy | generic

• Codex — append the printed [mcp_servers.axuse] block to ~/.codex/config.toml
• Claude Code — claude mcp add --scope user axuse -- node <path>/src/cli.js mcp
• OpenCode — merge the printed mcp block into opencode.json
• Antigravity / any MCP host — the printed mcpServers block

Verify the environment: node src/cli.js doctor.

The model-facing usage contract lives in SKILL.md — point your harness's skill system (or system prompt) at it.

Solver plugins (open core ↔ paid solvers)

axuse's core is CAPTCHA-agnostic and ships no solvers. Turnstile / hCaptcha / reCAPTCHA solvers are separate, commercially licensed packages that plug in through a thin, frozen seam (src/plugins/):

# install: drop a solver package into plugins/ (or list dirs in AXUSE_PLUGINS)
node src/cli.js plugins          # → ✓ captcha-pro@1.0.0 — providers: turnstile, recaptcha-v2, hcaptcha
node src/cli.js solve turnstile --url https://demo.turnstile.workers.dev/

From any MCP harness: ax_solve_captcha { provider, url? } and ax_plugins. Plugins that own capabilities (session vaults, network governors, guarded actions…) can also contribute their own MCP tools through a validated tools() export (ax_vault, ax_net, ax_guard, …) — same seam, same trust boundary. The ABI, the solver context, the tools() contract, and packaging/licensing guidance: docs/plugins.md. A complete free (PolyForm Noncommercial 1.0.0) reference solver lives in examples/plugin-turnstile-demo/.

Architecture

harness (Codex / Claude Code / OpenCode / Antigravity / …)
        │  MCP over stdio (JSON-RPC 2.0) — the universal integration layer
        ▼
src/mcp/ — thin, stateless-per-call adapter (hand-rolled, zero deps)
        │  one frozen command contract (src/core/commands.js)
        ▼
src/core/ — the state owner (Codex native-host / ZCode host pattern)
   ├─ controller.js  sessions, tabs, state_id, dialogs, auto-observe diffs,
   │                OOPIF frame registry (f-slot namespaced refs)
   ├─ cdp.js         launch/attach Chromium, browser-level WebSocket, flat sessions,
   │                Target.setAutoAttach for OOPIF auto-entry
   ├─ serialize.js   injected AX serializer: element-identity refs, shadow DOM,
   │                same-origin iframes (coordinate-translated), budgets
   ├─ diff.js        per-ref diff + text-line multiset diff + cost-based full fallback
   ├─ actuate.js     trusted Input.dispatch*, live ref resolution (frame-chain
   │                coordinate translation), combos, waits
   ├─ screenshot.js  one raster, byte budget, quality fallback, crop hints
   └─ errors.js     typed codes, retry hints, action_sent, side_effect
        │
        ├─ src/bridge/ — Codex-style extension backend for the user's daily
        │   Chrome/Edge: hub (TCP rendezvous, token auth, NDJSON) ←
        │   native-messaging host (framed stdio relay) ← MV3 extension
        │   (chrome.debugger = real CDP over the user's real browser)
        │   + installer (registry/HKCU, host manifest, launcher) + backend
        │   duck-typed onto the same command contract
        ▼
src/desktop/ — computer use (driver matrix)
   ├─ Windows: resident PowerShell + SendInput/GDI, DPI-aware — VERIFIED
   ├─ macOS:   JXA/CoreGraphics + System Events + screencapture/sips,
   │           display-point coordinates, env-gated with TCC diagnostics
   └─ (the driver interface is the seam for a real AX/UIA tree driver)

The patterns, and where each one comes from

Tool surface

Browser (always): ax_open, ax_open_many, ax_navigate, ax_go, ax_tabs, ax_observe, ax_click, ax_fill, ax_upload, ax_hover, ax_type, ax_press, ax_scroll, ax_select, ax_drag, ax_screenshot, ax_element_info, ax_evaluate, ax_wait_for, ax_events, ax_dialog, ax_close.

The ones that save the most steps:

• ax_fill sets a whole form in one call (text, selects, checkboxes, radios, switches, custom dropdowns, autocomplete) and can click submit.
• ax_observe {find:"text"} returns only the matching lines of a big page.
• ax_scroll {until:"text"} scrolls an infinite feed or virtualized list, in the page or inside a scrolling panel, until the text appears.
• ax_upload sets files on a file input; a click that opens a file chooser is reported instead of hanging.
• ax_open_many opens a bounded URL list sequentially, returns compact titles and accessibility excerpts, and closes temporary tabs by default. It is the batch equivalent of ax_open and avoids writing a custom MCP client.
• JS dialogs and new tabs opened by an action are reported in its result.

Desktop (Windows: verified. macOS: opt-in with AXUSE_ENABLE_MACOS_CUA=1 and host Accessibility/Screen Recording grants. Linux: automatic on X11/XWayland sessions with DISPLAY set): ax_desktop_screenshot, ax_desktop_screen_info, ax_desktop_click, ax_desktop_type, ax_desktop_press, ax_desktop_scroll, ax_desktop_windows, ax_desktop_activate, ax_desktop_drag.

The loop the model is guided into

ax_open            → FULL snapshot with refs (e.g. button "Sign in" [ref=e7])
ax_click {e7}      → returns the DIFF (removed/added/changed + text changes)
ax_type {e9, text} → returns the diff (value="…" appears)
…                  → screenshots ONLY for visual/canvas checks (budget-capped)

Cross-origin iframes appear in the snapshot as --- frame f1 (url) --- sections with f1:eN refs — same loop, same diffs, frame-stable refs.

Errors are facts, not strings:

{ "code": "REF_NOT_FOUND",
  "hint": "Refs are per-observation. Call ax_observe, then act on fresh refs.",
  "retry": "reobserve" }

Driving your daily browser (the Codex pattern)

axuse bridge install        # registers the native messaging host (Chrome + Edge hives)
axuse bridge                # hub (or it starts on demand with the MCP server)

Load bridge/extension unpacked in Chrome/Edge (Developer mode → Load unpacked), then ax_open { url }: while the extension is connected, an omitted backend picks it (the result reports backend; pin it with AXUSE_BACKEND=cdp|extension). Your browser, your logged-in sessions, tabs visible to you; ax_close closes only axuse's tabs. Input and navigation bring a hidden axuse tab forward first (background tabs get no requestAnimationFrame, so SPAs never finish wiring their handlers; AXUSE_VISIBLE_GUARD=0 opts out). Tabs are shared by every caller of one server, so tab_id is required once more than one tab is controlled (AXUSE_REQUIRE_TAB_ID=0 restores the implicit active tab). Tabs no call has touched for 30 minutes are closed (AXUSE_TAB_IDLE_MS, 0 = off), and the hub closes the tabs of a client process that disconnects. Top-level HTML/text data: URLs load through Page.setDocumentContent on this backend (Chrome refuses the navigation); other data: types need localhost. For long articles whose snapshot is cut or shortened, ax_observe {mode:"text"} returns the full readable text. The whole chain — native messaging framing, hub auth, CDP-over-chrome.debugger, diffed snapshots, trusted clicks — is covered by test/bridge.test.js.

Field notes (all established live against Edge 155 / Chrome 155):

• Branded Chrome silently ignores --load-extension (137+). Automated extension loads need Edge / Chromium / Chrome-for-Testing; manual unpacked loads work everywhere.
• Edge requires allowed_origins in the host manifest — with only allowed_extensions it reports "native messaging host not found". The installer writes both.
• On macOS, setup and bridge install also accept chromium and chrome-for-testing, and register the host in each browser's own NativeMessagingHosts directory.
• The Windows native host is a .bat launcher: cmd.exe relays the framed stdio pipes faithfully, where a compiled C# shim (Console.OpenStandardInput) dropped Chrome's stdin writes. Debug any install with AXUSE_BRIDGE_DEBUG=1 (hub + nm-host message tracing) and self.__axuseDiag inside the extension's service worker (readable via an attached DevTools/CDP session).

Honest scope notes

• macOS desktop control is opt-in because it can synthesize OS input. Set AXUSE_ENABLE_MACOS_CUA=1, grant the host Accessibility and Screen Recording in System Settings → Privacy & Security, then run node src/cli.js doctor. Coordinates are macOS global display points and returned desktop JPEGs are resized to the same point dimensions for direct click mapping. Linux desktop control mounts automatically on X11/XWayland sessions (needs DISPLAY; Xvfb works for headless hosts) — and it is structure-first too: the AT-SPI tree (via axuse's zero-dependency D-Bus client) mounts ax_desktop_ax_snapshot/ax_click/ax_set/ax_read like macOS, plus EWMH windows, RandR monitor layout, a screenshot budget ladder that downscales instead of erroring, and clipboard-paste typing when xclip is installed.
• The extension backend has no Target domain (chrome.debugger limits), so OOPIF frames are listed but not entered there; the CDP backend enters them.
• Anti-bot reality: axuse runs a real Chromium with a real profile, but it does not implement Codex's x-browser-agent traffic labeling or bot-detection handoff — sites that fingerprint automation may still block it. The bridge backend (your daily browser) is the most human-looking path.

For a non-MCP batch workflow, the same bounded operation is available from the CLI and accepts plain URL lists or Markdown containing links:

node src/cli.js open-urls sources.md --backend extension --output report.md

The generated report is intentionally honest: it contains page titles, access status, and bounded accessibility-text excerpts, not fabricated semantic summaries.

Development

node --test test/diff.test.js test/browser.test.js test/mcp.test.js test/desktop.test.js test/desktop-linux.test.js test/oopif.test.js test/bridge.test.js test/plugin.test.js

On macOS, enable the passive desktop capability gates explicitly:

AXUSE_ENABLE_MACOS_CUA=1 AXUSE_TEST_MACOS_DESKTOP=1 npm test

Tests are gated: browser/MCP tests skip when no Chromium-family browser is found; the OOPIF test spins up two loopback origins (127.0.0.1 + localhost); the bridge test registers + uninstalls a native messaging host and uses an extension-capable browser when one is installed (branded Chrome on current macOS builds is honestly skipped because it ignores automated --load-extension); desktop tests exercise passive screen/window discovery on macOS with AXUSE_TEST_MACOS_DESKTOP=1. A real macOS screenshot test is explicit with AXUSE_TEST_MACOS_SCREENSHOT=1 because Screen Recording is TCC-protected. The Linux desktop tests boot their own private Xvfb displays (and skip typed when Xvfb is not installed); they never touch your session. No test moves your real mouse or sends keys.

Debugging: AXUSE_BRIDGE_DEBUG=1 traces hub + native-host messages; self.__axuseDiag in the extension SW reports connect/disconnect history.

Every # SKIP in a suite run is explicit, typed, and audited: run TAP output through node tools/skip-audit.mjs and it fails when a skip is missing from test/skip-allowlist.json. CI enforces this on every lane.

macOS production reference — support matrix (browsers × macOS versions × arch), TCC permission model, failure taxonomy, the manual TCC validation lane, benchmarks, and known limitations with evidence: docs/macos-support.md.

License

Copyright © CTOL Digital Solutions (ctol.digital). All rights reserved.

Licensed under the PolyForm Noncommercial License 1.0.0 — see LICENSE. Use, distribution, and modification are free for any noncommercial purpose (personal use, research, education, charities, public institutions). Commercial use requires a separate commercial license from CTOL Digital Solutions (ctol.digital).