6Letters Unveils MOJO KING for Non-Invasive Testosterone Tracking

Digital healthcare startup 6Letters has officially launched MOJO KING, an innovative iOS application designed to facilitate non-invasive monitoring of testosterone-related physiological patterns using data from the Apple Watch. Announced on January 19, 2026, the app employs heart rate variability (HRV) as a key biometric signal to analyze fluctuations linked to male hormonal balance, allowing users to track their hormone levels without the need for blood tests or external sensors.

The current iteration of MOJO KING assesses biometric signals in relation to age-group baselines and 24-hour circadian rhythms. Users are classified into two categories based on their results: “Teto Guy,” indicating levels above the age-adjusted average, and “Egen Guy,” for those below. Results are displayed in an easy-to-understand visual format, which can be shared on social media platforms, including Instagram.

By offering a paid subscription, MOJO KING users can eliminate in-app advertisements and enable automatic, continuous measurements. This feature supports a shift from one-time readings to ongoing, trend-based hormone monitoring, tailored to individual lifestyles. The app is built upon a foundation of multiple patents and peer-reviewed scientific research, ensuring its reliability and efficacy.

To enhance the accuracy and personalization of the app, 6Letters is training machine-learning models using extensive medical datasets from organizations such as the UK Biobank, CDC, and Physionet. Insights from this research will inform the next generation of the company’s hormone analytics platform, pushing the boundaries of current health technology.

Innovative Approach to Hormone Monitoring

MOJO KING sets itself apart from conventional smartwatch fitness applications, which typically focus on metrics like heart rate and respiration during aerobic exercise. Instead, this app analyzes pre- and post-exercise changes associated with moderate-to-high-intensity resistance training, providing valuable insights into hormone-related responses to strength workouts.

In the future, 6Letters plans to expand MOJO KING with additional features, including hormone-dependent hair loss management and growth-phase optimization. Furthermore, the company is preparing to introduce MOJO QUEEN, a complementary application focused on female hormone analytics.

As part of its growth strategy, 6Letters is currently conducting a pre-seed funding round, with an estimated company valuation of USD 5 billion. The company anticipates completing its AI training based on extensive medical data and plans to apply for FDA 510(k) clearance in the first half of 2026. This will enable entry into the U.S. Remote Patient Monitoring (RPM) reimbursement market.

Empowering Users with Hormone Insights

“MOJO KING is designed to help users understand and manage hormone-related physiological signals in everyday life,” said a representative from 6Letters. By integrating scientific evidence, large-scale medical data, and wearable technology, the company aims to create a globally scalable digital hormone health platform.

As digital health continues to evolve, MOJO KING represents a significant step forward in personalized health monitoring, making hormone tracking accessible to a broader audience. With its user-friendly design and innovative approach, 6Letters is poised to redefine how individuals manage their hormonal health in the modern age.