Riiid

Riiid is a South Korean artificial-intelligence education company founded in 2014 in Seoul. Its consumer flagship is Santa, a mobile test-prep app. Santa is an AI-driven adaptive learning product, not a human-tutoring service: its value comes from a machine-learning engine that diagnoses a learner’s ability, recommends targeted questions and predicts exam scores. In 2025 Riiid rebranded to Socra AI, and riiid.com now redirects to socra.ai, though the Santa product continues.

Santa focuses on English-proficiency exams: primarily the TOEIC, and now the TOEFL via an official content partnership with ETS. The app covers Reading, Listening, Speaking and Writing, and its AI Tutor can auto-score Speaking and Writing using official ETS scoring. The personalization engine is trained on real test data, with reported average TOEIC gains of roughly 124-165 points after about 20 hours of study.

Santa monetizes through app subscriptions and time-limited passes, at about $16.49/month or $103.99/year, plus premium passes at $149.99 (30-day) and $239.99 (90-day). The company has raised about $250M total, headlined by a $175M round from SoftBank Vision Fund 2, and Santa has surpassed 5 million downloads concentrated in Korea, Japan and Taiwan. It best suits self-directed learners wanting efficient, data-driven exam prep rather than a live tutor.