REA for Claude Code: Reverse Engineer Windows Apps Step-by-Step

That's Claude code explaining how a real Windows app sends its requests. Every step points to the exact file and most

to the exact line. It used a tool called REA. REA stands for reverse engineer anything. It lets Claude code look

inside apps on your PC and work out how they do things. It's one of the fastest growing projects on GitHub, over 100,000

stars, most of them in the last week. Here's the thing. Claude code already reads code and runs tools on its own.

So, what does REA really add? I tested it on three open-source Windows apps, each one twice, with REA and without it.

Same question, same PC, real times and costs. First, we install REA in about 2 minutes. Then, one real example, start

to finish. Then, the scoreboard. And at the end, the rules, what you're allowed to look inside and what you're not.

Press Windows plus X and click terminal. Two quick checks first. Type node space {dash} {dash} version and press enter.

REA needs a recent node. Version 24 from 24.11 up is the safe pick. Mine says 24.18.

Then, type Claude space {dash} {dash} version and press enter. Any version number means Claude code is installed.

Not recognized? Both install videos are linked in the description. Now, type NPX space REA {dash} agents space setup and

press enter. NPX comes with node. It downloads a tool and runs it in one step. NPM asks, "Okay to proceed?" Type

Y and press enter. Give it about 10 seconds. REA's setup opens and asks, "Which agents should use REA?" It works

with others, too, like Code X, Cursor, and Gemini CLI. We want Claude code. Stop. This is important. Nothing's

ticked yet. Claude code is highlighted, so press space to tick it. The box turns green. Then, press enter. Now, REA shows

exactly what it'll change. Two things. It adds itself to Claude code settings, and it installs a skill, a set of

instructions Claude code can follow. It also says it won't install or upgrade other software, like Node or Java. Yes,

apply is already selected. Press enter. 2 seconds later, it's done. The last line says, "Restart Claude code to load

REA." Let's start Claude code in a new folder. Type mk dir space REA-test and press enter. That makes the folder.

Then, type cd space REA-test and press enter to move into it. Now, type Claude and press enter. Claude code

asks if you trust this folder. The highlighted choice is no, exit. Press the down arrow once, then enter. Let's

check that REA loaded. Type /mcp and press enter. MCP is how Claude code plugs in outside tools, and there it is,

REA connected with 170 tools. Press escape to close the list. Quick one. Is REA working for you? Type

works or paste your error below. I answer everyone. Want your AI tools set up properly? Subscribe. Now, let's give

it a real job. Our test app is Insomnia. It's a free app for testing APIs, the way programs talk to each other over the

internet. I paste a web address and click send. The answer comes back in a moment. Why an open source app? REA's

own rules say, "Use it on software you own or are allowed to examine." Insomnia is open source. Its license lets anyone

study its code. So, it's the legal pick for our test. More on the rules at the end. Want to follow along? The download

link is in the description, and you don't need an account. The prompt is in the pinned comment. Copy it, click into

Claude code, and press control plus V. Don't press enter yet. A good REA prompt has three parts. The feature you want

explained, where the app lives on your PC, and show me the evidence. That last part matters more than you'd think. I'll

show you why in a minute. But, here's where it gets tricky. Big apps ship thousands of library files. That's

ready-made code other people wrote. Insomnia has over 50,000 of them, all in one folder called node_modules. If REA

reads them all, the job takes about an hour and a half. So, this prompt adds one sentence. Skip node_modules and

analyze only Insomnia's own code. Now, press enter. Claude code asks to read outside this folder. Insomnia and REA

skill both live elsewhere. So, option one is right. Press enter. Claude code unpacks the app and skips the libraries.

556 files instead of 50,000. REA maps them in the background. Meanwhile, Claude code starts reading the files

itself. About 6 minutes later, there we go. Insomnia sends every request through libcurl, a well-known for web requests.

It runs in the app's main process, the part you never see. And every step points to the file it came from. Now,

fair question. Didn't Claude code know this already? Partly. I asked it from memory first with every tool switched

off. It knew the big picture, but it had no line numbers and some names were out of date. That's why the prompt asks for

evidence. Every line number here comes from the app on my PC. So, who found what? REA found the request engine

inside one giant file, down to the exact lines. But, it missed the handoff, how a request gets from the window to that

engine. Claude code read the code itself and filled that in. So, most of this answer is Claude code's. REA even rated

its own coverage as partial. Now, the real question. Does Claude code even need REA? Times change from run to

run. So, for a fair test, I ran the prompt twice more, back-to-back. Once with REA and once with REA switched off.

With REA, it took almost 8 minutes this time and $1.61. Without it, 3 minutes 20 and $1.13. Same

core answer, step for step. And each run found a small extra of its own. Why? Two reasons. Insomnia is an Electron app, a

website packaged as a desktop program. Its code ships as plain text and Claude code reads text just fine. And Insomnia

is well known, so Claude code already knew which names to search for. The dollar amounts are what the same work

would cost on pay-as-you-go pricing. On my Max subscription, the demo run used about 2% of my 5-hour limit. I did the

same with two more open-source apps. TextGrab copies text off your screen. It's a .NET app built with Microsoft's

toolkit for Windows apps packed into one big file. Without REA, Claude code was faster again. With REA, the file was too

big for two of its tools. The third one is where REA earns its place. Translucent TB makes your taskbar

see-through. It's compiled to machine code, raw instructions for your processor with no readable names. Plain

Claude code still found the answer. It used a disassembler, a tool that lists those processor instructions as text. It

came with Microsoft's C++ build tools, which happened to be on my PC. Most fresh PCs don't have them. And the

output is accurate, but very hard for us to read. REA plugs in Ghidra, a free tool from the NSA, the US security

agency. Ghidra turns machine code back into code that reads like a normal program. Same findings at nearly twice

the cost. Ghidra needs Java and a bit of setup. REA's Windows guide is linked in the description. That's one run each on

one PC on well-known open-source apps. So, treat it as a strong hint. My tip? For well-known Electron and .NET apps,

try plain Claude code first. For a compiled app like Translucent TB, when you want code you can read, REA with

Ghidra is worth the setup. Before you point REA at anything, a few honest limits. On Windows, REA support

for compiled apps is still experimental. It doesn't support firmware on Windows at all. That's the software inside

gadgets like routers. And every run eats into your plan. Anthropic safety checks can also interrupt some security work

like malware analysis. Claude code never stopped in any of my test runs on open source apps. Now the rules, straight

from REA's own page. It's not for getting around license checks or copy protection. And it's not for copying

someone's software or code. Your country's laws or the app's license can also restrict reverse engineering. Many

paid apps forbid it outright. So, what's fine? Open source apps within their license, your own software, and anything

you have clear permission to examine. And like a feature in a paid app, build your own version the clean way. Use the

app, note what it does, and write fresh code with your own design. Claude code can do that without REA at all.

And that's it. REA is set up in Claude code. You've seen what it adds, where Claude code does the job alone, and

where the line is. I picked the next video for you. It's on screen now.