Set up REA,
one step at a time.

How the pieces fit

The AI chat in your web browser can't open programs or files on your computer. A desktop AI app can, once a tool such as REA is connected to it. REA is the part that looks inside a program and reports what it finds.

Step 1

Get an AI app for your computer

Pick the one that matches the AI you already use:

• You use Claude in the browser. Install Claude Desktop and sign in with the same account.
• You use ChatGPT. Install Codex, OpenAI's coding agent, and sign in with your ChatGPT account.
• You already use a coding agent such as Claude Code, Cursor or Gemini CLI. Keep it and go to step 2.

Open the app once to finish signing in, then leave it. This guide shows Claude Desktop; the other apps follow the same steps.

Step 2

Install Node.js

REA runs on Node.js, a free program that many developer tools use. REA doesn't install it for you, so do this once:

1. Open the Node.js download page.
2. Choose the LTS version (“long-term support”) and the installer for your computer: a .pkg file on a Mac or an .msi file on Windows.
3. Open the downloaded file and click Continue or Next until it finishes. Keep the default options.

On Linux, use the instructions for your distribution on the same page. REA works with Node.js 22 (22.19 or newer), 24 (24.11 or newer) and 26 or newer.

Step 3

Open the terminal

• Mac: press ⌘ Command + Space, type Terminal and press Return.
• Windows: press the Windows key, type cmd and press Enter to open Command Prompt. Use Command Prompt rather than PowerShell for these steps.
• Linux: press Ctrl + Alt + T, or open Terminal from your apps.

Check that Node.js is installed. Type this line, then press Enter:

$ node -v
v24.11.1

If the terminal says command not found or is not recognized, close the terminal, open a new one and try again. A terminal opened before the installation can't see Node.js yet.

Step 4

Run REA setup

Click Copy, paste the command into the terminal and press Enter:

To paste: ⌘ Command + V on a Mac, Ctrl + V in Windows Command Prompt, or Ctrl + Shift + V in most Linux terminals.

The first time, npm asks before downloading REA. Type y and press Enter.

$ npx rea-agents@latest setup
Need to install the following packages:
rea-agents@6.3.0
Ok to proceed? (y) y

Step 5

Choose your AI app

Setup shows a list of AI apps. Use the keyboard:

1. Press ↓ to move to your app, for example Claude Desktop.
2. Press Space to tick it. The empty box ◻ turns into a filled box ◼.
3. Press Enter to continue.

┌  REA setup
│  Understand local apps and binaries from your terminal or agent.
│
◆  No agents detected. Choose any supported agent below.
│
│  Keys: ↑/↓ navigate · Space toggle · Enter confirm · Ctrl-C cancel
│
◆  Which agents should use REA?
│  ◻ Claude Code
│  ◼ Claude Desktop (Not detected · configuration is still available)
│  ◻ Codex
│  ◻ Cursor
│  ◻ Gemini CLI
│  …
│  ↑/↓ to navigate • Space: select • Enter: confirm
└

On a Mac or Linux, setup may also ask “Install Hopper for deep binary analysis?” Press Enter to keep No. You only need Hopper for compiled programs, and you can add it later from the native analysis setup.

Step 6

Approve the changes

Before it changes anything, setup lists exactly what it will do.

◆  Ready to review
│
│  CREATE  Claude Desktop
│          ~/Library/Application Support/Claude/claude_desktop_config.json
│          Add the REA MCP registration for Claude Desktop;
│          preserve unrelated configuration.
│
│  INSTALL  REA reverse-engineering skill
│          ~/.agents/skills/reverse-engineer-anything
│          Install or update the bundled REA reverse-engineering
│          skill and on-demand references.
│
◆  Apply these 2 changes?
│  ● Yes, apply / ○ No, cancel
└

• CREATE adds REA to your AI app's settings file. Your other settings stay as they are; if the file already exists, setup keeps a backup.
• INSTALL adds a short instruction set that teaches coding agents how to use REA.

Yes, apply is already selected. Press Enter. To stop instead, press Ctrl + C; nothing is changed.

Step 7

Restart your AI app

When setup finishes, it tells you what to restart:

◆  What you can do now
│  Agent access: Claude Desktop
│  Guided reverse-engineering workflows: installed
│  CLI: npx rea-agents capabilities
│  Try in Claude Desktop: "Explain how a feature works in
│  /path/to/app and show the evidence."
│
└  Restart Claude Desktop to load REA.

Quit the app completely, then open it again. Closing its window isn't enough:

• Mac: click the app, then press ⌘ Command + Q.
• Windows: choose Quit or Exit from the app's menu, or right-click its icon next to the clock and choose Quit.
• A terminal agent such as Claude Code or Codex: exit it and start it again.

You can close the terminal now.

Step 8

Ask your first question

Try REA on a small example app with an Export notes button. You don't need to run it; REA reads its code.

1. Download the example ZIP and unzip it: double-click it on a Mac, or right-click it on Windows and choose Extract All.
2. Copy the prompt below and paste it into your AI app. Don't send it yet.
3. Copy the path of the notes-example folder:
   • Mac: right-click the folder, hold ⌥ Option and choose Copy “notes-example” as Pathname.
   • Windows: right-click the folder and choose Copy as path. On Windows 10, hold Shift while you right-click.
4. Paste the path at the end of your message and send it. If your app asks whether it may use a REA tool, allow it.

You're set up. To understand that answer and check one detail yourself, continue with your first investigation. To try your own programs, pick a guide:

• Trace an Electron CSV exportDesktop apps built with web technology. No extra tools needed.
• See what happens when you clickWebsites, using Chrome or another Chromium browser.
• Recover a calculation from a gameCompiled programs such as .exe files. Needs Ghidra, Hopper or IDA.

If something goes wrong

Still stuck? Read the FAQ, ask in the REA community or report a problem. Include what you typed and what the terminal printed.