6Letters Unveils MOJO KING: A New Era in Testosterone Monitoring

Digital healthcare startup 6Letters has introduced a groundbreaking new application, MOJO KING, designed for non-invasive monitoring of testosterone-related physiological patterns. Officially launched on January 19, 2026, this innovative iOS app utilizes data from the Apple Watch to track changes in male hormonal balance through heart rate variability (HRV).

The app stands out by enabling users to monitor hormone-related trends without the need for blood tests or external sensors. By analyzing biometric signals against age-group baselines and 24-hour circadian rhythms, MOJO KING categorizes users into two distinct groups: “Teto Guy” for those with values above the average and “Egen Guy” for those below. This analysis is presented in a visually appealing format, making it easy for users to share their results on social media platforms, including Instagram.

Subscription Features and Future Developments

With a paid subscription, users can enjoy an ad-free experience and access continuous measurements, which allows for personalized tracking of hormonal changes over time. This feature shifts the focus from one-time readings to a more comprehensive approach to hormone monitoring, tailored to individual lifestyles.

6Letters has developed MOJO KING based on multiple patents and peer-reviewed scientific research. To enhance the app’s accuracy, the company is currently training machine-learning models using extensive medical datasets from reputable sources such as the UK Biobank, CDC, and Physionet. Insights gained from this endeavor will contribute to future iterations of the company’s hormone analytics platform.

The app also differentiates itself from conventional smartwatch fitness applications, which typically focus on heart rate and respiration during aerobic activities. Instead, MOJO KING examines changes associated with moderate-to-high-intensity resistance training, providing users with valuable insights into hormonal responses to strength workouts.

Expansion Plans and Funding

Looking ahead, 6Letters aims to expand MOJO KING by introducing additional modes, including options for managing hormone-dependent hair loss and optimizing growth phases. The company is also preparing to launch MOJO QUEEN, a complementary digital health application focused on female hormone analytics.

As part of its growth strategy, 6Letters is conducting a pre-seed funding round, valuing the company at approximately USD 5 billion. The startup anticipates completing AI training based on its extensive medical data and plans to seek FDA 510(k) clearance in the first half of 2026. This will enable the company to enter the U.S. Remote Patient Monitoring (RPM) reimbursement market.

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