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The Subscription Problem

Subscription services: hate them or loathe them, they sadly exist. More and more companies are moving towards them. It started with paying for subscriptions to watch movies and TV shows on Netflix, then free services added subscriptions to avoid ads, and then companies that sell physical devices started adding subscriptions to use them.
Some companies are now locking basic features of physical products behind subscription paywalls - features that should be available in the hardware you already purchased.

Examples of Hardware Subscriptions

BMW wanted to include heated seats with a subscription, but after backlash, they dropped it. But many companies continue with this model:

8sleep

Sleep mattress for $2,500 that requires a subscription service to use

Whoop

Doesn’t even “sell” their device - only sells membership for one or two years and you get the device for “free”
No company has gone further in this business model than Whoop. You can’t buy the device outright - you must subscribe to use it.

Device Limitations

Beyond the subscription issue, the Whoop 4.0 has several frustrating hardware limitations that could be addressed through custom firmware:

Sensor Restrictions

Whoop has a few sensors: heart rate, temperature, and blood oxygen sensors, but:
  • Temperature sensor: Only measured once a day, during sleep
  • Blood oxygen sensor: Only measured once a day, during sleep
  • Heart rate sensor: Works continuously (this is the main feature)
The hardware is capable of more frequent measurements, but these limitations are imposed by the official firmware and app.

Alarm Limitations

The alarm functionality has a critical restriction:
The alarm can only be set to ring once a day instead of for multiple periods.
This arbitrary software limitation makes the device less useful than it could be.

Freedom Through Reverse Engineering

By reverse engineering the Whoop 4.0’s BLE protocol, you can:
  • Use the device without requiring a subscription
  • Read sensor data directly from the hardware
  • Create custom applications and integrations
  • Potentially unlock features limited by the official firmware
  • Own and control the device you’ve already paid for

What's Possible

The device can measure heart rate, store and retrieve data, and vibrate as an alarm. Through reverse engineering, you can access these capabilities directly via Bluetooth Low Energy (BLE) without the Whoop app or subscription.
This guide shows you how to take back control of your hardware and use it on your terms.

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