Duolingo
Duolingo (NASDAQ: DUOL) is a Pittsburgh, Pennsylvania based learning technology company best known for the Duolingo language-learning app, the world's most-downloaded education app, offering courses in more than 40 languages including Spanish, English, French, German, Italian, Portuguese, Japanese, and Chinese. Founded in 2011 by Luis von Ahn and Severin Hacker, Duolingo has expanded its consumer learning footprint beyond languages with Duolingo Math, Duolingo Music, a newly rolled-out Chess course, and Duolingo ABC for early literacy, all delivered through the same gamified, streak- driven mobile experience. The Company also operates the Duolingo English Test, a digital English-proficiency exam accepted by thousands of higher- education institutions, certification programs, and government agencies worldwide as an alternative to TOEFL and IELTS. Duolingo monetizes through Super Duolingo and Duolingo Max subscriptions, in-app advertising, in-app purchases, and Duolingo English Test fees. The company surpassed 50 million daily active users in Q3 2025 and reported 41% revenue growth in Q2 2025. Duolingo does not publish an official public developer API, SDK, or developer portal; integrations with the Duolingo English Test (score-send to institutional CRMs such as Slate) are handled through a private API-key program negotiated directly with accepting institutions. Community- maintained reverse-engineered clients exist against the unofficial https://www.duolingo.com/api/1 surface but are not endorsed by Duolingo.
Index entry only — little beyond a description and a link, and nothing machine-readable enough for an agent to act on without a human reading the site first.
API Evangelist profiles Duolingo the way a machine reads it — 3 machine-readable artifacts, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Duolingo scores 8.7/100 (minimal), with a separate agent-readiness read of 0/100 (human only). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.
Kin Score
How this is scored →scored 2026-07-27 · rubric v0.5
How we profile Duolingo
Each block below is one kind of artifact we hold for Duolingo. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
GraphQL 1
Where a provider ships GraphQL, the schema is the contract. We profile it alongside the REST surface so the whole interface is legible in one place.
GraphQL schemas published by this provider.
Duolingo GraphQL Schema
This directory contains a conceptual GraphQL schema for Duolingo, the world's most-downloaded language-learning app. Duolingo does not publish an official public GraphQL or REST...
GRAPHQLSecurity Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Resources
Every other property we hold for Duolingo — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Documentation 1
Reference material describing how the API behaves
Build 1
SDKs, sample code, and the tooling you integrate with
Access & Security 2
Authentication, authorization, and security posture
Learn 1
Tutorials, courses, talks, and written guidance
Operate 1
Status, limits, changes, and where to get help
Company 7
The organization behind the API
Scroll within the panel for all 7 ·
Other 11
Properties that don't map to a standard resource type
Scroll within the panel for all 11 ·
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