People compare the two because both mark writing passage by passage and both can be used without going through an institution. They are built to answer different questions, though, and which one you want depends on the question you have.
GPTZero is an AI detector. It estimates how likely a text is to have been written by AI, and gives a probability for each sentence alongside one for the whole document.
UnTXT is an AI pattern checker. It shows which parts of your writing are built the way a model builds them, and tells you why for each one. It also marks the parts that sound like one particular person. There is no percentage anywhere in it, and it makes no claim about who wrote anything, because people follow those patterns too.
So one tells you how likely, and the other tells you which paragraph, and why. Neither is wrong. If somebody needs a number, we do not have one to give them.
| UnTXT | GPTZero | |
|---|---|---|
| What comes back | Passages marked AUTHENTIC or FLAGGED, each with its reasoning | A probability per sentence and per document |
| A percentage score | None, on purpose | Yes |
| Marks what sounds like you | Yes, in gold | Not its purpose |
| How the reading is done | Two AI models argue each passage out, and a third settles ties | Its own trained model |
| Bulk upload and classroom tools | No. Up to 50 documents a request through the API, and an overnight queue | Yes, in its educator product |
| LMS integration | No | Yes |
The GPTZero column describes what it publishes about itself. Check its own site for what it offers today; we would rather you did that than took our word for somebody else's product.
UnTXT marks where a student sounds most like themselves as well as where the writing follows AI patterns, which gives you something to open a conversation with that is not an accusation. Any analysis exports to a dated PDF. The Educator plan carries 1,300 CVT a month, which is about twenty-three analyses of 1,100 words.
GPTZero has an educator product with bulk upload and classroom management. UnTXT has neither in the app and no LMS integration, so if that is what your department runs on, GPTZero is the better fit and we would say so.
A fixed monthly plan from £8.40, tax included, with an allowance of credit. Go past the allowance and the extra is metered and billed at month end, so an analysis is never refused halfway through a document. The first 1,000 words are free. GPTZero publishes its own free tier and plans.
UnTXT, if what you want is to know which parts of a piece of writing sound machine-made and why, and to decide for yourself what to do about it.
GPTZero, if you need a probability score, bulk processing or an LMS connection.