Direct answer
The Scribbr extension is a free Chrome browser add-on from Scribbr that lets you run a plagiarism and AI check on text you are writing in Google Docs or on a web page, and it also plugs into Scribbr's citation generator [1]. It is a writing-support tool built on Scribbr's own detection engine — it is not a Turnitin client and it does not produce the Turnitin AI writing report or similarity report your university sees. If your goal is to know the exact score a marker will see before you submit, the extension is a convenience layer, not a substitute for an actual Turnitin check.
What Does the Scribbr Extension Actually Do?
The extension works inside the browser you already write in. Once installed, you highlight a passage, click the Scribbr icon, and the selected text is sent to Scribbr's checker, which returns a similarity reading and a list of matched sources [1]. Scribbr positions the underlying tool as comparing your text against a very large index of web pages and publisher content, and it shows a similarity percentage plus the individual matches rather than a single opaque number [2]. That is genuinely useful as a first pass: it catches copy-paste leftovers, half-paraphrased paragraphs, and quoted material you forgot to attribute.
What it does not do is reproduce institutional scoring. Scribbr's checker and its separate AI detector are Scribbr products with their own models, thresholds, and reporting layout [2]. Turnitin's AI writing indicator is a different instrument entirely — it estimates the share of qualifying prose in a document that was likely generated by AI, and it deliberately suppresses the figure when its confidence is low [3]. Two engines with different training data, different text segmentation, and different confidence rules will disagree on the same paragraph, and neither one "wins" the argument — the institutional tool is simply the one whose number counts.
There is also a practical ceiling on what a browser extension can see. An extension checks the text you hand it, in the window where you hand it over. It does not see your full .docx structure, your reference list formatting, your headings, or how the document will be ingested by a submission portal. Students who check a few highlighted paragraphs and then submit a whole dissertation are testing a sample, not the document.
Finally, the extension is a convenience product, not an audit trail. It leaves you with a similarity reading you cannot attach to anything, whereas a real report is a PDF with a cover page, a score, flagged passages, and a source list — the artefact you can actually compare against feedback [2].
Is the Scribbr AI Detector the Same as Turnitin?
No. They are separate commercial products from separate companies, and their outputs are not interchangeable [2][3]. The confusion is understandable because both are marketed to students with the same vocabulary — "AI score," "percentage," "flagged text" — but the underlying measurement is different, and so is the consequence of being wrong.
The most important mechanical difference is the confidence threshold. Turnitin only displays an AI writing percentage when it has enough signal to stand behind it; below that bar the report shows an asterisk-style low-confidence indicator rather than a precise figure [3]. That design choice matters enormously in practice, because it means a document can look "clean" on one platform and flagged on another without either platform malfunctioning. Scribbr's detector, like most third-party detectors, applies its own decision rules and reports its own confidence band [2]. A student who sees 0% in one place and 34% in another has not found a bug — they have found two different instruments.
Segment-level highlighting is the second divergence. Turnitin's AI report colours the specific spans it considers likely AI-generated and reports the percentage against qualifying prose, which excludes things like reference lists and heavily quoted blocks [3]. That means a short AI-assisted introduction inside a long, largely original essay can produce a modest percentage that looks alarming out of context, while a shorter document with the same absolute amount of AI text can produce a much higher one. A single headline number from any third-party tool cannot tell you how an institutional report will frame the same text.
The third difference is scope and audience. Third-party checkers are built for the writer; institutional reports are built for the marker and are released to students only when the instructor enables that visibility [4]. So even a perfect prediction from an outside tool would not change what you are permitted to see, or when. What it can change is your decision about whether to revise before submitting — which is the only decision that is still yours to make.
How Can You See Your Real Turnitin AI and Similarity Report Before You Submit?
The only way to see the report your institution will generate is to generate that report. Turnitin's student-facing documentation is explicit that report visibility is controlled by the instructor: a submission may produce a similarity report that students can view, or it may not, and the AI writing indicator appears only when the institution has that feature enabled and the confidence threshold is met [4][3]. That is why "my friend could see theirs" is not evidence that you will see yours.
What you can control is the draft you hand over. A pre-submission check that runs the same detection engine, on the same file type, with the same document boundaries, gives you the two things an extension cannot: the actual AI percentage as Turnitin computes it, and the actual similarity report with its match overview and source list [4]. That turns an anxious guess into an edit list — you know which paragraphs to rewrite, which citations to tighten, and whether the document is genuinely ready.
There is a second, quieter reason to check properly rather than approximately. Turnitin's similarity report is a structured document: a match overview, numbered sources, and highlighted overlaps that a marker reads in a specific order [4]. Seeing that structure once, before it counts, teaches you how your own writing will be read. Students who have previewed a real report stop over-citing defensively and stop under-citing accidentally, because they have seen how a 12% score is actually assembled.
One practical caution: a check that adds your file to a student paper database can create its own problems on a resubmission. Non-repository checking — where the document is compared but not retained in the shared database — keeps the preview from contaminating your later official submission [4]. That distinction is worth confirming with any service before you upload a full dissertation.
The Scribbr extension is a reasonable first sweep for stray matches in a Google Doc, but it was never designed to tell you what your marker's Turnitin report will say. If you want the report itself — the AI percentage, the flagged spans, the similarity match overview, delivered as PDFs you can read and act on — turnitin0 runs that check on your own draft before you submit, with no student-paper-database retention and results typically back in under 15 minutes.
※ Turnitin0.com - Actual Turnitin AI Report Cover, Score, Flag And Similarity Summary
Get [Real Turnitin](https://www.turnitin0.com/) AI & Similarity Report
FAQ
Is the Scribbr extension free to use?
Yes. The Chrome extension itself is free to install, and it gives you a similarity reading on selected text inside Google Docs and on web pages [1]. The full, downloadable report behind Scribbr's checker is a paid product, so the free layer is a preview rather than a complete report [2].
Can the Scribbr extension detect AI-generated text?
Scribbr offers an AI detector as a separate product from its plagiarism checker, and the extension is best understood as a convenience entry point to Scribbr's checking tools rather than a dedicated AI-detection client [1][2]. In either case, its AI verdict is Scribbr's own model, not Turnitin's, and the two can legitimately disagree on the same paragraph [3].
Why did my AI score differ between Scribbr and Turnitin?
Because they are different detectors with different training data, segmentation, and confidence rules [2][3]. Turnitin also withholds a precise AI percentage when its confidence is low, which alone can make a document look different across platforms without either tool being wrong [3].
Does checking with a third-party tool affect my official Turnitin submission?
Only if the service adds your file to a shared student paper database. Non-repository checking compares your document without retaining it, so the preview does not create a match against your later official submission [4]. Confirm the retention policy before uploading a full dissertation.
Will I be able to see my Turnitin AI report after my instructor's check?
Not automatically. Report visibility is an instructor setting, and the AI writing indicator appears only when the institution has that feature enabled and the confidence threshold is met [4][3]. Previewing a report beforehand is the reliable way to know what you are working with.