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Health technology, privacy-first design, and the research behind what a ring can actually measure.

A customs inspection checkpoint at a border crossing — where Ultrahuman Ring Pro just cleared after months blocked by Oura patent disputes

Latest Wearables Ultrahuman Ring Pro Lands in the US at $479 Ultrahuman Ring Pro just cleared US customs after an Oura patent block and is selling at $479 with no subscription. That price validates Pulsyn's entire thesis: on-device health tracking should not cost more than a flagship smartphone. James Hoffmann May 26, 2026 11 min read Read article

Pebble's $75 Index 01 and the Great Smart Ring Divergence James Hoffmann May 26, 2026 12 min read

Why Stress Scores Are the Most Fabricated Metric in Wearables Every major wearable gives you a stress score between 0 and 100. That number is not a measurement. It is a proprietary blend of heart rate variability and secret sauce with no clinical definition. Pulsyn shows you the raw HRV and the context instead. James Hoffmann May 26, 2026 13 min read

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LATEST ARTICLES

A medical electrocardiogram monitor showing heart rhythm data, representing the raw physiological signal behind HRV analysis

What HRV Actually Measures and Why Your Recovery Score Is a Marketing Invention HRV is not a score. It is a noisy physiological signal that consumer wearables clean, compress, and repackage as a recovery percentage with no medical validation. This post explains how the sausage is made, why the math does not support the marketing, and what Pulsyn does instead. James Hoffmann May 26, 2026 12 min read

A close-up of a smartphone processor chip, the same hardware that runs Pulsyn's on-device health AI without ever sending your biometrics to a server

How On-Device AI Actually Works: Why Your Health Data Never Leaves Your Phone On-device AI means your health data never leaves your phone. Here is the architecture, the constraints, and why it makes subscriptions unnecessary. James Hoffmann May 25, 2026 13 min read

A dark metallic smart ring on a textured surface, representing the last independent hardware in an industry racing toward subscriptions

The No-Subscription Smart Ring Is Not Dead. The Industry Just Wants You to Think So. Oura filed for IPO. RingConn got pulled from Amazon. Ultrahuman and Luna are banned in the US. A Reddit user asked if the no-subscription smart ring dream is dead. It is not. But the remaining options are smaller, founder-led, and built on economics that venture capital hates. James Hoffmann May 25, 2026 11 min read

A digital lock concept representing how wearable companies trap user health data behind proprietary APIs and subscriptions

The API Trap: How Wearable Companies Make Your Health Data Disappear When You Cancel Most wearable APIs are not built for you. They are built for partners who build features that keep you subscribed. Here is how the data lock-in actually works, and how Pulsyn does the opposite. James Hoffmann May 24, 2026 13 min read

View through an airplane window at night, representing the disconnected environments where most health trackers fail but Pulsyn keeps working

Your Sleep Tracker Should Work on a Plane. Ours Does. Most health trackers treat your phone as a dumb pipe to their cloud. When you turn on airplane mode, the app becomes a brick. Pulsyn's architecture assumes the opposite: your phone is the computer, the database lives locally, and the cloud is an optional extra. James Hoffmann May 23, 2026 13 min read

A dark abstract visualization of encrypted data streams and digital security

How Pulsyn Encrypts Your Health Data: SQLCipher, 600,000 PBKDF2 Iterations, and Why We Do Not Know Your PIN A technical deep-dive into Pulsyn local-first encryption stack: SQLCipher, AES-256-GCM, 600,000 PBKDF2 iterations, and why we intentionally cannot recover your data if you lose your PIN. James Hoffmann May 22, 2026 11 min read