A Scribbr AI detector alternative for whole theses and long essays
IsThisAiWritten is a free Scribbr AI detector alternative with no word limit at all, so a 15,000-word thesis goes through in one check instead of thirteen. It needs no account, runs in your browser and never uploads your text. Scribbr's AI detector is also free, needs no sign-up and lets you run as many checks as you like, so the usual reason to look elsewhere is length: each submission stops at 1,200 words.
Choose IsThisAiWritten when the document is long: one free check covers a whole thesis, nothing is uploaded, and the methodology is open for anyone to read. Scribbr is a sensible free choice for short pieces, and for Spanish, German or French text, which we don't support. Both are free, so trying both costs nothing.
Scribbr's AI detector is already a good free option
It is worth saying up front. Scribbr's checker asks for no account, puts no cap on the number of checks and says it does not store or share your data. It also sorts text into four categories (AI-generated, AI-generated and AI-refined, human-written and AI-refined, and human-written), which is more nuance than many detectors offer. If your essays are under 1,200 words and in one of its four languages, you may not need anything else.
The case for an alternative comes down to longer work and to how much you can learn about the score.
IsThisAiWritten vs Scribbr
Scribbr details are from its AI detector page at the time of writing.
| IsThisAiWritten | Scribbr AI Detector | |
|---|---|---|
| Price for basic use | Free | Free |
| Sign-up required | No | No |
| Word limit per check | No limit. Minimum 50 words, best from 150 | Up to 1,200 words per submission |
| Daily limit | None | Unlimited checks |
| Where your text is processed | In your browser. Never uploaded | On Scribbr's servers |
| Data stored | Nothing, because we never receive it | Says it does not store or share your data |
| Long documents (novels, theses) | One pass, at any length | Must be split into 1,200-word submissions |
| Sentence-level highlighting | Sentence map, relative within your text | Feedback on each section, labelled AI-generated, AI-refined or human |
Why students look for a Scribbr AI detector alternative
A thesis does not fit in 1,200 words. A 15,000-word master's thesis means thirteen submissions, each returning its own percentage, and no overall view of the document. Scribbr's FAQ itself recommends scanning longer pieces of text rather than single sentences or paragraphs for the best results, and a whole thesis gives a detector the most to work with.
The other gap is information. Scribbr's accuracy answer is candid that no detector is fully accurate and points to its own research, where the best premium tool reached 84% and the best free one 68%. It does not put a number on its own detector. Its page also points readers who want a more advanced check to QuillBot's detector.
What IsThisAiWritten adds
One check, one map for the whole thesis
Paste the full text and you get one outcome (Human, Mixed, AI or Inconclusive) with a confidence word, instead of thirteen percentages. The sentence map then ranks which sentences look most AI-like compared with the rest of your own text, across every chapter at once, so you can see whether one section stands out. It is a relative ranking, not a verdict on each sentence. See AI detection for long documents.
Every word read, nothing uploaded
You can paste the thesis or open it as a .docx or .txt file, which is read on your own computer. The detector reads every word rather than a sample, and the unpublished chapters never leave your browser. How it works and how it is tested is published on our methodology page. Like any detector, it can be wrong in both directions, so treat a result as a reason to look closer, not as proof.
If you stick with Scribbr for a long document
That is a fair choice, especially for a thesis in German, French or Spanish. A few habits make split results easier to read. Cut at natural breaks, such as sections or chapters, rather than at exactly 1,200 words, so each submission is a coherent piece of writing. Keep a simple table of the score for each part, and look for the one or two sections that stand out from the rest instead of averaging them. Leave out reference lists, block quotations and tables, which say little about how you write. And whatever the scores, keep your drafts and notes. If a score is ever held against you, they matter more than any percentage, as our article on what to do when you're wrongly flagged explains.
Scribbr has real advantages. It reads Spanish, German and French as well as English. Its four-way labels separate text a person wrote and then refined with AI from text AI generated outright, a distinction we don't attempt and one that matters if you used a grammar or paraphrasing tool on your own writing. It sits alongside a plagiarism checker, proofreading and a citation generator that students already use.
Scribbr's checker also needs no download, while our first check fetches a 131 MB model, which is a nuisance on a phone or a slow connection.
Keep using Scribbr if your essays are short, or written in Spanish, German or French. Its AI-refined label is also something we can't match.
Other Scribbr alternatives
QuillBot has the same 1,200-word free limit, six scans a day, and more than 20 languages; its Premium plan removes the cap (QuillBot alternative). GPTZero accepts up to 150,000 characters per scan with a free account, within a 10,000-word monthly allowance (GPTZero alternatives). Students who can't run Turnitin's AI detector themselves can read our Turnitin alternatives for students, and the student guide covers what to do with any result.
Sources
- Scribbr AI Detector and FAQ (limits, privacy, languages, categories, accuracy), checked October 2026
- QuillBot AI Detector, checked October 2026
- GPTZero FAQ, checked October 2026
- GPTZero for students, checked October 2026
Questions
Do Scribbr or IsThisAiWritten keep my text?
Scribbr says it does not store or share submissions to its AI detector. IsThisAiWritten never receives your text in the first place: the detector runs inside your browser.
Is this AI written? Check it now.
Free, no sign-up, no word limit. The check runs in your browser, so your text never leaves your device.
Check text freeIsThisAiWritten is not affiliated with, endorsed by or sponsored by any company named on this page. Product names belong to their owners. Facts about other products come from their public pages on the date shown and may have changed since.