Sjeel Koster

Sjeel Koster is a B2B SaaS growth leader and Fractional CMO specializing in scalable go-to-market strategy, ICP validation, and retention mechanics for high-growth tech scale-ups. With over a decade of executive marketing experience, Sjeel was an early hire at SEOshop through its acquisition by Lightspeed, where she led EMEA marketing and helped scale operations through major M&A and public offering phases. Later serving as Director of Demand Generation and Marketing Operations at EVBox and co-founding HolidayHero, she works with European tech companies to align positioning, outbound systems, and customer lifetime value. Sjeel regularly shares GTM frameworks at conferences like SaaSiest and writes for Churned on predictive churn prevention, subscription lifecycle management, and sustainable SaaS expansion.