Sebastiaan Cortjaens is a Dutch entrepreneur and co-founder of the independent watch brand MAEN, which he established in 2017 alongside Jules van Helvoort. His entry into the horological industry was driven by a lifelong interest in watch collecting and a professional background that bridged the gap between law and entrepreneurship.

Before founding MAEN, Cortjaens practiced as an international tax lawyer. During this tenure, he gained exposure to the commercial side of the watch industry while working with a watch brand as a client. This experience, combined with his dissatisfaction regarding the quality and design of accessible timepieces on the market, prompted him to transition into the industry himself. He eventually partnered with Van Helvoort, a computer and motion designer, after the two discovered a shared vision for creating high-quality, vintage-inspired timepieces sold directly to consumers.

Based in Stockholm, Sweden, Cortjaens has been a central figure in defining MAEN’s brand identity and operational strategy. The name of the brand, derived from the Old Dutch word for “moon,” reflects a commitment to classic design cues and the founders’ heritage. Cortjaens has emphasized a philosophy of “timeless proportions,” focusing on smaller, wearable case dimensions and high technical specifications, such as the use of Swiss-made movements from Sellita and ETA.

Under his co-leadership, MAEN has expanded from its debut moonphase collection, the Lunar Classic, to several successful lines, including the Hudson diver, the Skymaster chronograph, and the Manhattan integrated-bracelet series. Cortjaens is actively involved in the meticulous development process of each model, which typically spans 8 to 14 months and involves extensive prototyping to ensure manufacturing precision.

Throughout his career with the brand, Cortjaens has maintained a focus on transparency and value, advocating for a direct-to-consumer model that minimizes overhead. His contributions have helped establish MAEN as a notable participant in the global microbrand community, with a presence in over 90 countries and collaborations with prominent horological figures and artists. Today, he continues to oversee the brand’s design and commercial expansion from its Stockholm headquarters.