Open source · macOS · Apache 2.0

Eyes, ears, and hands for AI‑assisted mobile development and test.

A local debug server that gives AI coding agents live access to your iOS simulators, Android emulators, and physical devices — logs, network traffic, screenshots, and UI control. No cloud. No telemetry.

curl -fsSL https://quern.dev/install.sh | bash

Eyes

Screenshots, UI accessibility trees, screen summaries, and annotated overlays. Your agent sees exactly what's on screen.

Ears

Real-time logs, crash reports, build output, and full network traffic capture. Every signal your app emits, captured.

Hands

Tap, swipe, type, boot simulators and emulators, install apps, and intercept or mock HTTP traffic. Full control over the runtime.

How it works

Quern runs as a local server on your Mac. It connects to iOS simulators and Android emulators via their native toolchains, and to physical devices over USB. It captures logs and network traffic through lightweight adapters, and exposes everything as MCP tools that AI coding agents can call directly.

76 MCP tools across 11 categories, lazy-loaded so they don't bloat your context window. Works with Claude Code, Cursor, and any MCP-compatible client.

Context usage after loading 3 Quern MCP tools — only 4% of the context window used
Quern architecture — giving AI agents eyes, ears, and hands for mobile debugging

What you can ask

Boot an iPhone 16 simulator, build my app, and show me any errors.
Boot a Pixel 9 emulator, install the APK, and check for crashes.
Mock the /api/users endpoint to return a 500 and see how the app handles it.
Find the last crash report and tell me what caused it.
Take a screenshot and tell me what's on screen.
Show me all the API calls made during login.
Intercept the auth token refresh and replace it with an expired one.
Boot three different devices and compare the layouts across platforms.
Open a live preview of my device so I can see what the agent is doing.
Check if the analytics payload includes the right event when I tap checkout.
Install the latest build on my physical device and walk through onboarding.
...and anything else you can think of.

Requirements

The install script detects your platforms and sets up everything automatically.