I generally love my Whoop band, but there's no question that the company's subscription-only model isn't for everyone. A few weeks ago, a hobbyist created an app that can connect to your old Whoop 4.0 strap. I loved the idea, since an independent app sounds like a great way to keep your data private and to make use of an otherwise obsolete piece of hardware. But as I worked through the steps of compiling and testing the freshly posted code, I noticed more apps like it popping up on Reddit and Github.

Since then, some of these Whoop-compatible apps have been taken down, at least one of those at the request of a Whoop executive. Here is what I learned in talking to several of those apps’ developers, and whether I think independent Whoop apps have a future. (Tentatively: yes.) 

“In cases that violate our IP, trademarks, or terms of use, we have reached out to individuals to take down their apps,” a Whoop spokesperson said to me in a statement. The developers that I’ve spoken to, for their part, believe that what they’re doing is legal and ethical.

Whoop’s position is that the value of the Whoop platform is in its proprietary analysis and features, which others have tried to imitate but cannot directly replicate. The company makes an API available to developers, through which they can access the data Whoop has processed. Using the API requires working through Whoop’s system—meaning the user must have a Whoop membership and allow the company to process their data. This is a different scenario than what’s going on with the independent projects I’m writing about today. These new projects aim to let individuals use Whoop hardware without any contact with the company itself, and without ever having had a subscription.

But before I get into why I’m excited about the independent projects, I’d like to include Whoop’s entire statement to me, so you can see where they’re coming from: 

“WHOOP is always excited to see how passionate our members are about using data to better understand their health and performance. WHOOP is designed as an integrated hardware, software, and data platform. It is not possible to access WHOOP proprietary health insights, coaching, analytics, or signature metrics and features—including Recovery, Strain, Sleep scoring, Stress Monitor, Healthspan, and WHOOP Coach—outside of the WHOOP membership experience. The value of WHOOP comes from turning continuous physiological data into validated, personalized, and actionable insights.

“We support third-party app development with our developer APIs and have even created an easy-to-use developer platform. However, not all third-party apps or independent tools are created, reviewed, or authorized by WHOOP.”

The promise of independent Whoop apps

Whoop has always been a high-end product. It’s a screenless fitness tracker, now in its fifth generation, that you wear as a wristband. It captures your heart rate and motion data, and sends that to an app on your phone, which in turn sends it to the cloud to be processed. You pay for this service—$239/year is the typical price—and in turn Whoop gives you detailed analysis of how well you’re recovering from your exercise.

Whoop’s app is good, in my opinion; it goes well beyond basic tracking, and I still think it’s worth the money if you’re a devoted athlete or you really like to nerd out about how well your body is handling the stress you put it under. 

But for as long as Whoop has been around, there have been people wondering if they could use the device for their own purposes. While we finally have competing devices with no required subscription (like the Fitbit Air), there are also a lot of old Whoop devices out in the world. Nearly everyone who had a Whoop 4.0 has probably since upgraded to the 5.0 (seeing as the company sends out the newer version for free), leaving their old strap as e-waste. What if there was a way to repurpose that old hardware? 

That’s the idea behind apps like Noop, Goose, Wearable, and more. These newer apps aren’t the only ones compatible with Whoop hardware, but they appeared recently and they quickly overtook several older, long-simmering projects that had been working on the same question: How can an independent app read data from a Whoop device? Because if a free app can read the device’s data over Bluetooth, you could use the hardware for your own purposes without the Whoop app or subscription service.

How a non-Whoop app can talk to a Whoop band (and why it’s taken so long to get here)

The idea of an independent app for a Whoop band isn’t new. Several projects have tried it over the years, with varying levels of success. One I found useful was called Whoomp, and it was simple to use: you load a special web page in your browser, and your computer begins communicating with the Whoop device over Bluetooth. (A public version of Whoomp used to be available here.) The first time I tried it was a thrill: I put on an old Whoop 4.0 device and saw my heart rate on my computer screen. I could press a button on the web page and feel the device buzz on my wrist. The device hadn't been connected to my phone for years; I felt like Dr. Frankenstein bringing the dead to life through the power of technology.

As several developers told me, a Whoop device, fresh out of the box, communicates certain things over Bluetooth. If a computer or phone communicates back in the right way, the two devices can become paired and bonded, and send data and commands back and forth. To have a functional Whoop-like app, the phone has to know how to hold up its end of the conversation.

The Whoop device uses BLE, or Bluetooth Low Energy. That’s a type of connection that many other wearables and devices also use. But Whoop has not publicly released instructions for exactly how phones or computers can access Whoop’s features over BLE. The official Whoop app knows what to say to the device to get it to bond and to transfer data, but independent developers had to figure out, through trial and error, how to decode the language that the device “speaks.” This was a slow process, and until recently, programs like Whoomp were for people who wanted to tinker with the device, knowing that they only had partial functionality. A project like Whoomp could read your heart rate, sure, but it’s not a drop-in replacement for the official Whoop app or subscription. 

How the independent Whoop apps appeared (and disappeared)

A few weeks ago, developer Johnathan Middleton posted on the Whoop subreddit that he had managed, with the aid of Claude Code, to decode more of the Whoop 4.0 communication protocol than had previously been known. He posted the code for an iPhone app and a server that you can run on your own computer to process the data. The project was on the software repository Github under the name "my-whoop," which has since changed to "Wearable." It is still available here, but to use it, you’ll need to know how to compile and sideload an iPhone app—not a beginner-friendly process. 

I spoke with Middleton on a video call. He’s a software engineer in his day job, and says he created the Wearable project over a weekend. He used Claude Code to automate some of the more tedious tasks, like sending signals to the device and checking how it responded. Middleton’s work built on the decoding work accomplished with earlier projects, which he credits in his notes. (That’s how I found out about Whoomp, one of the projects cited.) The resulting app looks a bit like Whoop’s, with scores and analysis that Middleton calculates based on published algorithms; they won’t necessarily match Whoop’s proprietary scores.

Middleton announced his project on the Whoop subreddit on May 30. On June 2, another developer announced a project called Goose, which is meant to work with the newer 5.0/MG bands. On June 7, yet another developer posted the first of many announcements about a project called Noop that builds off both Wearable and Goose to communicate with both types of bands. 

I’ve been in touch with Noop’s developer over email; he indicated his pronouns but did not disclose his name. In the initial announcement, he said proudly that he used $1,500 worth of AI tokens to develop the app. More Reddit posts followed, and the code has been updated hundreds if not thousands of times in the short time the project has been online. Redditors on the Whoop forum have been rolling their eyes at “all these vibe coded apps” because, yes, more have popped up since then. (Here’s Bandmate from June 4,  Seraph from June 11, a modified version of Goose also from June 11, and Edge from June 13.)

On June 17, I noted that Noop’s code was gone from Github (the platform that hosts code for pretty much all these projects). Noop’s developer said that he hadn’t heard anything from Whoop directly, but that Github took it down. He appealed the decision and the repository was reinstated. In the meantime,  he set up a mirror of the code here.

Whoomp disappeared from GitHub even earlier, on June 10. Its developer, John Fitzgerald, told me that Robert Johanson, Whoop’s VP of software, reached out to ask him to take the project down. Johanson also reached out to Middleton, the developer of Wearable, with a similar request, but Middleton kept his code available, and so far it’s still online. 

Goose was supposed to launch its app over TestFlight (a beta testing platform for iPhone apps) on June 13, but never did. I have not been able to get in touch with the developer. The code is still available on Github, but archived as read-only, suggesting that the project is dead.

How you run an unofficial Whoop app

When I decided to test Wearable—Middleton’s app, which was the first I came across—I faced quite the learning curve. Apple doesn’t allow hobbyists to compile apps and share them widely, at least not without a lot of extra steps. This makes sense from Apple’s perspective, since a mystery app could do all kinds of things to your iPhone you may not want it to. (For one thing, Apple requires that an app be signed by a developer, so you know who it came from.)

Bigger developers will often distribute an app for testing through a platform called TestFlight. You may have used this if you’ve ever beta-tested an iPhone app. Eventually, of course, such a developer might aim to have the app available on the real App Store. But if you just want to tinker with some code you downloaded, you need to be able to compile the app with Xcode, then sideload it (that is, transfer it locally, usually over a USB cable). To do that, well, let’s just say there were a lot of steps I had to figure out. I managed to build Wearable and load it onto my iPhone; later, when I was testing Noop, I found an unsigned .ipa (app) file that another hobbyist had created from Noop’s code, and I installed it via Sideloadly, which shortcut the process a bit—although that’s still risky, because it isn't easily confirmed that the .ipa contains the app I think it does.

The process is simpler on Android, but again, risky. Someone can give you an .apk file, which is already compiled and ready to install. Installing is as simple as clicking a link to the .apk from your Android phone, and tapping a button to say that, yes, you know you probably shouldn’t install this, but you want to anyway. 

But do these apps work?

I tried out several of the apps I’m writing about, with varying levels of success. Wearable detected my 4.0 strap and showed my live heart rate, but never managed to fully sync all my data. Noop, tested on an Android, managed to work with my 4.0 for a short time, but then I started getting errors. Noop on my iPhone was able to read data from my MG strap. Nothing I tried was 100% functional 100% of the time. 

That’s not unusual when you’re trying out code that’s still under development. Maybe I screwed up somehow, or maybe the apps are just buggy. It would take more methodical testing on my part to narrow down why I’m getting the problems I am. I’ve seen posts on Reddit from people who had more success than I did in getting Wearable and Noop working; Middleton showed me his phone with Wearable working smoothly.

If I took the time, I could possibly figure out what’s going wrong on my end and contribute some fixes to the code. That’s a nice thing about open source development: People work together to test and develop something that everyone can use. If the projects can survive Whoop’s legal threats, and if the developers stay interested enough to maintain the projects over time, we may have some useful, robust Whoop-alternative apps in the future. 

I’m looking forward to that. Reverse engineering, as these projects are called, is generally legal as long as the developer is not directly copying the company’s work or violating its terms of service. But most hobbyist developers aren’t prepared to fight legal battles even if they would theoretically win them, so takedown requests can often be enough to chill development. Aside from Noop, the projects I mentioned haven’t seen active development in at least the past week or so. I haven’t seen any new copycat apps on the subreddit, either. Feels pretty chilly to me.

Why I don’t think this is the end of alternative Whoop apps

For years, Whoop was the only device of its type. I wrote more about the state of smart bands here, but to summarize, there’s nothing special anymore about having a heart rate sensor on a wristband. Whoop’s branding and its top-notch app are the only advantages it has as a device; plenty of folks seem willing to abandon the platform if they can get an app for free, a device for cheap, or both.

Whoop surely knows this. The company is no longer pinning its business model to a single device (or app subscription), but has been branching out into the healthcare space. They now offer blood tests, which are pricey and repeatable. Earlier this year, Whoop joined Medicare’s ACCESS program. The Mayo Clinic and medical device company Abbott have both invested in Whoop, according to Forbes. The Whoop device and app may be the company's best-known products, but they're not the only way the company plans to make money.

Looking to the future, I hope that the Whoop-compatible apps stick around, and I think it’s likely that they will be legally able to. But will there be enough hobbyist developers with enough enthusiasm to debug, maintain, and distribute the apps, especially knowing that Whoop is watching over their shoulder? Will people who have old Whoop straps take a chance on these apps when they could just buy a Fitbit Air for $100 and a lot less hassle? 

Those are the questions I’m pondering. I’d love to have a reliable, free alternative to the Whoop app, or even to the Google Health app. Wearable devices are incredibly personal—they know every time your heart beats—and I don’t love that the only way to use these devices, in most cases, is to share that personal data with a large corporation. I think we should have independent apps, especially ones that work with abandoned tech. Here’s hoping they stick around, and keep improving.