Amazon's Halo Band, a wearable device that tracks various aspects of a user's health and wellness, was widely criticised by health experts and others as highly invasive.

Launched in August 2020, the Halo Band enabled users to track and evaluate their physical activity, sleep, and nutrition. However, privacy concerns were expressed about scans users were asked to share of themselves in minimal clothing to measure body fat percentage and how Amazon could potentially use or share the sensitive health data collected.

Although Amazon claimed to delete body scan images after processing, the fact that they were sent to the cloud made many people uncomfortable. Concerns were also raised that anonymised data could potentially be de-anonymised, especially with location information.

In addition, the device's microphones constantly listened to the user's voice to analyse their tone and emotional state - a feature seen as creepy by many. The fact that Amazon declined requests for independent privacy audits of the Halo Band was also criticised.

The criticism led to attention from members of the US Congress and, in April 2023, Amazon announced the shutdown of its Halo division, discontinuing all Halo devices including the Halo Band. 

The decision came amidst broader layoffs at Amazon and struggles in the competitive fitness tracker market.