GPTZero
Detector for AI-generated writing
We publish a full Four-Mismatches fit assessment for the student-facing exam tools first. For this one, the facts below are what we have verified — run the Four Mismatches Test on it yourself for your own students.
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 classifier scoring text on 'perplexity' (predictability) and 'burstiness' (sentence-to-sentence variation), with sentence-level highlighting.
Why it was built — Tell whether text was written by a human or an LLM, for academic integrity, hiring and publishing.
Who built it
- Company
- GPTZero
- Founders
- Edward Tian · Alex Cui
- HQ / origin
- New York City, USA
- Founded
- 2023
- Model
- B2B / B2C
- Languages
- English
- Pricing
- Freemium + API
We record durable facts only — no funding-raised or user-count figures. Unverified fields are marked [TBD] rather than guessed.
Where it sits
GPTZero is on the EdTech AI 100 map, in assessment & academic integrity, built in United States.