I Tested The Viral Github Repo That Reverse Engineers Anything (REA + Claude)

0:00There's a GitHub repository that has been on an absolute rocket ship to Mars this month in terms of popularity. That repo is reverse engineer anything or REA. Before October, the repo was popular, but it had under 10,000 stars on GitHub, and now it's got well over 330,000 stars. And people aren't just starring it on

0:20GitHub, they're actually using it. In fact, it's been downloaded over half a million times in October alone. So, in this video we are going to cover what this repo is, how you can get it installed, and how you can use it to reverse engineer and clone apps today. REA is a tool that lets AI agents like Claude or Codex look inside the guts of an

0:43app and see how it was all put together. You see, when you download an app on your computer, you aren't actually downloading the source code that the developer wrote, you are downloading a compiled version of that code. The code that the developer writes is meant for humans to read. Compiling turns it into machine code, which is just millions of tiny instructions that are meant for the

1:06processor. And during the process of compiling, the names, comments, and structure that made it readable get stripped out. Reverse engineering is the work of taking that machine code and trying to figure out what the original program was doing and what the original code may have looked like. The funny thing is, even though this repo blew up recently, the tools it exposes to agents have actually been around for

1:30decades. One tool that this repo exposes is IDA, which was actually developed in the 90s. It was really popular with cybersecurity researchers that were trying to reverse engineer viruses and malware. A famous example is Stuxnet, the computer worm that sabotaged Iran's nuclear equipment. Researchers at Symantec spent months using IDA and other similar tools to take apart and understand the attack without ever

1:57having the original source code. Another tool that REA exposes to agents is Ghidra, and this tool was actually built by the NSA and then released to the public in 2019. REA takes these tools and a few others and wraps them in an MCP server and a CLI so that your agents can easily use them. Ultimately, it allows your agents to peek deep into an application and figure out

2:24how it was built. Okay, let's dive in and I'll show you how you can get this set up. So, the easiest way to set this up is probably to just ask your coding agent. Both Claude and Codex can easily do this, here's the prompt that I gave Claude to set this up. I'll put it in the

2:41description of the video. You will need to approve a couple prompts and then restart your agent when it's done so that it can pick up all of the new tools that were installed. And if you decide to run the setup manually via npx, the first thing it will ask you to do is pick which agents should

2:58get REA. It supports a long list, Claude Code, Codex, Cursor, Gemini, and about 20 other agents. Now one quick tip during this process, if you plan on reverse engineering large applications, I would recommend increasing Ghidra's startup timeout. I kept running into issues because the timeout was way too short, so I had Claude update it to 15 minutes. Once everything is set up, you can really just talk to your agent like normal and it will reach out to REA either via MCP or the CLI when it needs to look inside of

3:37an application. To test REA out, I had to reverse engineer and clone an app called Raycast. This is an app that I use every single day. If you've never used it, Raycast is a launcher for the Mac. Think of it like Spotlight, but on steroids. You hit a hotkey, a search bar pops up in the middle of your screen, and

3:57then you type whatever you want to do. You can quickly find and open really any application on your Mac. I've used it a lot for quick file searching because it has much better file search capabilities than our native on a Mac. Probably the main thing I use it for, though, is managing my clipboard history. With just a quick hotkey I can see all of the items I have recently added to my clipboard which is a lifesaver when half

4:25your day is spent copying and pasting. It also has a pretty cool built-in calculator that can do all sorts of useful calculations and conversions. Anyway, that's just a handful of what's in there. Raycast ships with dozens of built-in features, and then there's a whole store of extensions that can live on top of this application. All right, so now let's get into how I

4:49actually built this clone. It came down to three core steps. First, I had Claude use REA to dig through Raycast and figure out how it works on the inside. No code yet. Everything it found went into a folder of notes. Some of what it found was big picture, high level stuff. For example, it found that Raycast has

5:11four main layers. First, a native Mac app that owns the windows and the hotkeys. Second, a React interface that draws everything you see. Third, a Node backend that holds almost all of the logic. And lastly, a few different Rust pieces for the database, file search, and the calculator capabilities, but the part that really paid off was the small stuff that it found the details that you would never get from

5:41screenshot. After compiling the notes, I had the agent build the clone from those notes. It went one feature at a time, starting with the main app in the launcher, and then it added app search capabilities followed by file search, followed by clipboard history, and lastly, it built the calculator. The last step was to iterate and work through the bugs, and this part was actually kind of cool, because whenever I found a bug, instead of going through the laborious exercise of debugging, the agent just went back to the original notes it had taken, and those notes frequently showed it exactly how the original app addressed the

6:20issue. For example, one bug I found was that the launcher always opened on my main monitor, even when I was working on my second monitor. I reported this bug. The agent looked up its notes, found a screen setting that the original Raycast application had, and fixed the bug. It also fixed a couple other window related bugs along the way, and the whole

6:42fix only took a few minutes. All right, let's take a look at the Raycast demo that my agent built first and foremost. This is an app launcher to replace Spotlight. So it should be able to quickly find and launch apps. So let's see if I search Safari here you'll see it pop up. I'm not going to open it for this demo but you can see

7:05can quickly find my apps and launch them. Let's go into this clipboard history here, which is the feature that I use the most on Raycast. And as you can see, I've got a bunch of things in my clipboard, I've got images, text. I can quickly open this action menu, copy it to whatever app I currently got open, and

7:24copy it to my clipboard. It's all pretty quick and pretty smooth, just like the real Raycast. It's got this Snippets feature which is... pretty cool where you can create reusable snippets that... It's basically for any text that you want, always at your fingertips, whether it's a prompt, maybe an email address, phone numbers, things like that. It's got a great search files option

7:52just search my resume and see. Yep. And you can choose to open it, you can choose to copy the path, which I really like for... Agents, giving the full file path and being able to copy that easily or reveal it in Finder is always handy. It even has some built-in AI functionality where you can...

8:11come in here and... wire it to your ChatGPT accounts or your Claude accounts which is sweet so In the real Raycast, you have to pay premium for these features. And with this built-in clone, you can just point it at Codex or point it at Claude, you don't have to pay for the AI features.

8:32So I really like it. It's really smooth. It's really quick. There were some bugs that we worked through. But again, like I said, working through those bugs was pretty easy with REA. Now, I will say that REA is not magic and it can't see everything about an app's source code. There was definitely some back and forth and there was some trial and error during this process,

8:55but it is a very helpful tool. It's a lot better than trying to clone an app via just screenshots and some detailed prompting. So that's REA. It won't hand you anyone's source code, but it does let your agent look inside an app instead of guessing from the outside, that's the difference between a mediocre clone that kind of looks right and one

9:17that looks, works, and feels right. Let me know in the comments what you plan to use REA on And if you liked this video, please smash the subscribe button, hit the like button, help that YouTube algorithm out. Thank you all and I'll see you in the next one.