A11y Bridge — Android Accessibility HTTP Bridge
Control Android devices through a 16KB Accessibility Service that exposes the live UI tree over HTTP (localhost:7333). ~50ms to read any screen, click by text without coordinate math.
Prerequisites
- Android device connected via USB with USB debugging enabled
- ADB installed and accessible in PATH
- Android SDK (build-tools 34, platform android-34) — only needed to build from source
Setup
Install pre-built APK
Download the latest APK from Releases, then:
# Install
adb install openclaw-a11y.apk
# Enable accessibility service
adb shell settings put secure enabled_accessibility_services \
com.openclaw.a11y/.ClawAccessibilityService
adb shell settings put secure accessibility_enabled 1
# Forward port
adb forward tcp:7333 tcp:7333
# Verify
curl http://localhost:7333/pingBuild from source (optional)
chmod +x build.sh && ./build.shUsage
Read screen (~50ms)
# Full UI tree
curl http://localhost:7333/screen
# Compact mode (only interactive/text elements)
curl 'http://localhost:7333/screen?compact'Returns JSON with all UI elements: text, bounds, clickable, editable, etc.
Click by text
# Click element containing "Settings"
curl -X POST http://localhost:7333/click \
-H "Content-Type: application/json" \
-d '{"text": "Settings"}'
# Click by resource ID
curl -X POST http://localhost:7333/click -d '{"id": "com.app:id/send"}'
# Click by content description
curl -X POST http://localhost:7333/click -d '{"desc": "Navigate up"}'Tap coordinates
curl -X POST http://localhost:7333/tap -d '{"x": 540, "y": 960}'Health check
curl http://localhost:7333/pingWorkflow
- Read:
curl http://localhost:7333/screen→ JSON with all UI elements - Find: Locate target element by text/role in the JSON response
- Act:
curl -X POST /click -d '{"text":"Send"}'→ click by text, no coordinates - Repeat
Multi-device support
When multiple devices are connected, specify the target with -s <serial> for all ADB commands:
adb -s <serial> forward tcp:7333 tcp:7333API Reference
| Endpoint | Method | Description |
|---|---|---|
/ping | GET | Health check |
/screen | GET | Full UI tree as JSON. Add ?compact for interactive elements only |
/click | POST | Click by text, id, or desc (JSON body) |
/tap | POST | Tap coordinates x, y (JSON body) |
Performance
| uiautomator dump | A11y Bridge | |
|---|---|---|
| Read UI | 3-5 seconds | ~50ms |
| Click | Calculate bounds → input tap x y | {"text": "OK"} |
| Full cycle | 5-8 seconds | 100-200ms |
Fallback
If the A11y Bridge service is not running (check with /ping), fall back to traditional ADB commands:
adb shell uiautomator dump /sdcard/ui.xml && adb pull /sdcard/ui.xml
adb shell input tap <x> <y>