Riiid bet AI knowledge tracing could replace test prep — SoftBank paid $175M to see

AI education company: the Santa TOEIC test-prep app in Korea, Japan and Taiwan, R.Test diagnostics for US exams, and licensed knowledge-tracing AI for education companies.

That deep-learning knowledge tracing — inferring from a few answers what a student knows — could replace hours-long standardized tests and the tutors who game them.

Founded in Seoul in 2014 by Y.J. Jang, Riiid shipped Santa, a TOEIC prep app that adapted to each answer instead of lecturing — and became the default English-test tutor for Korean students.

Santa moved into Japan through distributor Langoo and hit No.1 among Android education apps by sales in its first week, with sales up 400% a year. At the peak of the 2020-21 edtech boom — global edtech VC reached $16.1B in 2020 — SoftBank's Vision Fund 2 led a $175M Series D (May 2021) so Riiid could chase the bigger prize: replacing one-shot standardized testing via R.Test in US public schools. It bought Langoo that October, then acquired English-content provider Qualson (Real Class) in December 2023, with closing set for Q1 2024.

Riiid operates as a combined AI-plus-content education group — Santa/Riiid TUTOR across North Asia, Qualson's Real Class in Korea, R.Test in the US, and B2B licensing of its knowledge-tracing AI — still SoftBank-backed and independent.

Knowledge tracing turned a drill app into a data flywheel: every answer made the score predictions — and the product — better.

Starting with one standardized exam (TOEIC) gave the model a clean, measurable objective before attacking messier tests.

The 2021 SoftBank round bought a decade of runway, but raised the bar: proving the model beyond consumer test prep became existential.

Acquisitions of distributors and content owners hedged the bet — distribution and content were the moats AI alone couldn't conjure.

A data moat from one niche — TOEIC drills — funded a shot at the whole testing industry. But when the boom priced your round, buying content companies is how an AI story stays credible.

As of early 2024, with the Qualson deal set to close in Q1, Riiid runs three lines: consumer test prep (Santa/Riiid TUTOR) across Korea, Japan and Taiwan; Qualson's Real Class premium English content and corporate training arm Meganext, with Qualson CEO Sooyoung Park in a larger role; and R.Test, its rapid SAT/ACT diagnostic for the US. Its core AI is also packaged as APIs and custom solutions for education companies and public organizations — the direction Jang describes as applying the technology anywhere, regardless of region, language, or domain.