Both UnTXT and GPTZero detect AI-generated writing at the sentence level and are available directly to the public without institutional affiliation. This page compares the two tools on their current publicly available features.
| Feature | UnTXT | GPTZero |
|---|---|---|
| Sentence-level detection | ✓ | ✓ |
| Named signal categories | ✓ 10 types | ✗ (probability score per sentence) |
| PDF report export | ✓ | Paid plan |
| Free tier | 5,000 words on sign-up | Limited but large free tier |
| Subscription required | No — pay-once bundles | Paid plans available |
| Credit expiry | 365 days (purchased) | Monthly (subscription) |
| Role-based interface | ✓ (Student/Teacher/Professional) | ✗ |
| Multi-currency pricing | ✓ 14 currencies | USD primary, but support available for GBP, EUR and INR |
| CVT credit gifting | ✓ | ✗ |
| Public direct access | ✓ | ✓ |
Comparison based on publicly available information about both tools as of early 2026.
UnTXT uses ten independently-weighted detection modules: SPIKE (AI vocabulary), SYNTAX (repetitive structure), FORMAL (hedging language), HUMAN (genuine markers — a positive signal), TEMPLATE (boilerplate phrasing), FRONTED (fronted adverbials), FORENSIC (style inconsistency), RHETORIC (AI rhetorical structures), PUFF (inflated/promotional language), and FORMULA (challenge-and-future-outlook template). Each flagged passage is colour-coded by the module that detected it, so users see not only that a passage is flagged but which type of AI pattern it matched.
GPTZero provides sentence-level highlighting with a probability score per sentence and a document-level score. It uses its own detection model trained on a corpus of AI and human writing.
The practical difference: UnTXT informs the user why a passage is flagged and how to fix it; GPTZero informs them how likely it is AI. Both approaches serve different editorial needs.
UnTXT has a Teacher role providing Standard Mode (HIGH RISK / MEDIUM RISK / POSITIVE), PDF export of analysis reports, and teacher-sized credit bundles (Test / Class / Batch) valid for 365 days.
GPTZero has an educator product with bulk document upload and classroom management features. UnTXT does not offer bulk document upload or LMS integration in its current public form.
UnTXT: Pay-once credit bundle model. No recurring subscription. Purchased credits valid for 365 days. Free tier: 5,000 words on sign-up.
GPTZero: Free tier with word limit; monthly subscription plans at various price points. Monthly subscriptions mean unused capacity is lost at end of each billing period.
Choose UnTXT if: You want per-passage signal categorisation (why each passage is flagged), annual credits, PDF export, or multi-currency pricing.
Consider GPTZero if: You need bulk document processing, LMS integration, or prefer a broad probability-score approach to per-signal categorisation.