Skip to content
Addestra
Whole-curriculum AI tutorsUnited States

CK-12 Flexi

Free AI tutor built on open courseware

The Four Mismatches · CK-12 Flexi

Built for another system

Assessed for a Commonwealth / Global-South student (as an import).

  • CurriculumFail

    Built on US-standard open courseware, not local exam boards — though its WhatsApp delivery suits low-bandwidth markets.

  • LanguageFail

    English-only.

  • PricePass

    Free — a non-profit, not paywalled.

  • InfrastructurePass

    Available over WhatsApp and a Chrome extension, which degrade gracefully on a patchy connection.

Free and unusually accessible (it works over WhatsApp) — but a US curriculum in English, so still an import for a local exam.

addestra.com · The Four Mismatches Test. A single fail means it was built for a different system.

Independence: Addestra builds learning products too (MathsTutor, TinkerWell). We never review or score our own, and no tool pays to be listed or to rank higher — how we assess fit.

What it does

What the AI actually does — A GPT-4-class chat tutor grounded in CK-12's own curriculum library; on web, a Chrome extension, and WhatsApp.

Why it was built — Extend CK-12's free, open, curriculum-aligned resources into an always-on AI tutor that isn't paywalled.

Who built it

Company
CK-12 Foundation (non-profit)
Founders
Neeru Khosla · Murugan Pal
HQ / origin
Palo Alto, California, USA
Founded
Foundation 2007 (Flexi live by Dec 2023)
Model
B2C
Languages
English
Pricing
Free

We record durable facts only — no funding-raised or user-count figures. Unverified fields are marked [TBD] rather than guessed.

The fit assessment

The scorecard above scores CK-12 Flexi on the four axes on which exported EdTech fails to fit a local system — assessed for a Commonwealth / Global-South student (as an import). The verdict: Free and unusually accessible (it works over WhatsApp) — but a US curriculum in English, so still an import for a local exam. For the full framework, see the Four Mismatches Test.

Where it sits

CK-12 Flexi is on the EdTech AI 100 map, in whole-curriculum ai tutors, built in United States.

Related & alternatives

Sources