Pepper

Pepper gives AI agents eyes and hands inside iOS Simulator apps.

It injects a lightweight dylib into any running simulator app — no source changes, no SDK, no build step. The dylib opens a WebSocket server inside the app process, and your AI agent connects through MCP to see what's on screen, tap buttons, inspect state, intercept network calls, read the heap, and debug layout issues. Over 60 tools, all available through natural language.

Why

AI coding agents are powerful, but they're blind to what's actually happening in a running app. They can write code and read logs, but they can't see a broken layout, tap through a flow, or inspect why a view isn't updating. Pepper closes that gap.

It's also built for a second audience: developers who build surprisingly complex apps with AI but hit a wall when something breaks. If you've never opened Instruments or typed an LLDB command, Pepper gives you visibility into your app without learning traditional debugging tools.

Install

pip install pepper-ios

This gives you pepper-mcp (the MCP server) and pepper-ctl (a CLI). If you're using Claude Code with the repo cloned, .mcp.json handles config automatically.

Other MCP clients (Cursor, Claude Desktop, etc.)

{
  "mcpServers": {
    "pepper": {
      "command": "pepper-mcp"
    }
  }
}

Homebrew

brew install --HEAD skwallace36/pepper/pepper

Tap: skwallace36/homebrew-pepper

What It Can Do

Once connected, your agent can:

• See the screen — structured view hierarchy, not just a screenshot. The agent knows every label, button, and text field, their frames, traits, and accessibility identifiers.
• Interact like a user — tap, scroll, swipe, type, toggle switches, dismiss keyboards. All touch input goes through IOHIDEvent injection, the same path real fingers take. Works identically for UIKit and SwiftUI.
• Inspect runtime state — read and mutate properties on live objects with vars_inspect. Check Core Data stores, UserDefaults, keychain entries, cookies, clipboard contents.
• Debug what went wrong — capture console output, intercept network traffic, read crash logs, profile performance, inspect the responder chain, audit accessibility, visualize view layers and constraints.
• Control the environment — change locale, push notifications, toggle dark mode, rotate the device, simulate network conditions, manage the simulator lifecycle.

Parameter docs are built into every tool — your MCP client surfaces them automatically.

How It Works

Pepper uses DYLD_INSERT_LIBRARIES to load a dylib into the simulator process at launch. The dylib starts a WebSocket server on a local port. The MCP server (pepper-mcp) connects to that WebSocket and translates MCP tool calls into commands the dylib executes inside the app.

Because it runs inside the process, Pepper has access to everything the app can see: the full view hierarchy, the Objective-C runtime, live object graphs, network delegates, and the HID event system. No private APIs, no entitlements, no jailbreak — just dyld.

Adapters

Adapters are optional app-specific modules — deep link routes, icon mappings, custom tab bar detection. Without one, Pepper runs in generic mode and works with any app. Set APP_ADAPTER_TYPE and ADAPTER_PATH in .env to load one.

Development

Architecture guide: dylib/DYLIB.md · Tool reference: tools/TOOLS.md · Troubleshooting: TROUBLESHOOTING.md

About This Project

Pepper is an open-source tool and a learning piece. It's built to be useful to the iOS community and to demonstrate what's possible when you give AI agents deep runtime access to native apps. Fork it, rip it apart, adapt it to your workflow.