Jackson Shuttleworth

Leads the team responsible for Duolingo's most impactful feature (streaks) at a $14B company that doubled in value in six months, with direct ownership of the 600+ experiment program driving 9M+ users to year-long streaks. Their core argument: Test everything obsessively when you have scale -- 600+ experiments on a single feature in four years can generate a competitive moat of human psychology insights that no amount of intuition can replicate. The evidence is specific: 600+ experiments on streaks in four years, roughly one every other day. Furthermore, changing CTA from 'Continue' to 'Commit to my goal' produced a massive retention win. 9 million users with year-plus streaks, built through iterative experiment-driven feature development. In Jackson Shuttleworth's own words: "Streaks is the most impactful feature. We have, right now, over 9 million users with a year plus streak. If you look at the numbers, I think it's been our biggest growth lever." (Quantifying the business impact of the streak feature at Duolingo.)

Leads the retention team at Duolingo, a $14B company that doubled in value in six months, where the streak feature he oversees is the single most impactful feature driving growth -- with over 600 experiments run on it in four years and 9 million users maintaining year-plus streaks. Their core argument: Retention is the single most important lever -- Duolingo's streak feature proves it. The evidence is specific: Duolingo's streak feature has 9 million users with year-plus streaks -- equivalent to a large city's population using the app daily for over a year. Furthermore, changing the CTA from 'continue' to 'commit to my goal' was a massive win, discovered through systematic copy testing infrastructure. Early Duolingo streaks were XP-based, causing users who set ambitious goals to lose streaks despite doing multiple lessons -- simplifying to 'one lesson per day' unlocked dramatic improvement. In Jackson Shuttleworth's own words: "Streaks is the most impactful feature. We have, right now, over 9 million users with a year plus streak. If you look at the numbers, I think it's been our biggest growth lever." (On the enormous impact of retention-focused feature.)