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The popular scores, side by side

Detectors ask who wrote a piece. Plagiarism checkers ask whether it was copied. Editors ask whether it reads well. Verdict asks what it adds. Here is what each one does, how, and what it costs.

Checked on 2 November 2026 against each vendor's own pricing page, in the currency it lists. Plans change often; tell us if something is out of date.

Tool and the question it answers	How it works	Pricing	Free	Notes
Expulp VerdictWhat does this piece add beyond what AI already knows and what is already published?	Breaks the piece into claims and checks each one against what a model would say, what is already online and what others submitted before. Every claim is weighed for credibility and usefulness, and the piece is read both as of its publication date and against today's web.	Quick read free. Full verdict one credit: $1 each, 10 for $5, 50 for $20. Plans from $9 a month for 150 credits. Every credit comes with five quick reads. Credits last 90 days.	3 quick reads a day, 5 with a free account. Anything analysed before is free.	Shows its reasoning claim by claim, so you can see why. Takes longer than a detector: up to a minute for a quick read, one to two for a verdict. Fiction is still experimental.
GPTZeroWas this written by an AI?	Reads the whole text and returns a probability that it is AI-written, with sentence highlights. Paid plans add a plagiarism check and a replay of how a document was typed.	Premium €9.99 a month for 300,000 words, Professional €19.99 for 500,000, billed yearly.	10,000 words a month, 10,000 characters per scan.	Fast and popular with teachers. Rewording a text changes its answer, and it sometimes flags human writing as AI.
Originality.aiIs this AI-written, and is it copied?	AI probability and plagiarism matching for the whole text, plus readability and fact-check hints. Scans whole sites and has a Chrome extension that watches writing as it happens.	Pro $14.95 a month for 2,000 credits (one credit per 100 words, two with plagiarism); yearly $12.95. Enterprise $179 with API access.	A small daily allowance.	Made for marketing teams publishing at volume. Like any detector, a paraphrase changes its verdict without changing the content.
CopyscapeDoes this text appear somewhere else on the web?	Matches exact wording against its web index. Copysentry watches your pages for copies every day or week.	3 cents a search for up to 200 words, 1 cent per extra 100 words: about 16 cents for a 1,500-word piece. Copysentry from $4.95 a month.	A limited search by URL.	The reliable choice for catching copies. It cannot see paraphrase, and it says nothing about ideas.
TurnitinDoes a student's work overlap known sources, and was it AI-written?	Compares submissions with its database of papers and the web, and adds an AI-writing score for institutions that license it.	Sold to schools and universities on quote, not to individuals. Individuals can use iThenticate: $125 per manuscript, without AI detection.	None.	The standard in education and academic publishing. Its AI score is advisory, and the company says not to act on it alone.
GrammarlyIs this well written, and does it contain AI text or plagiarism?	A writing assistant for grammar, tone and rewriting. The Pro plan adds a plagiarism checker and an AI detector; Authorship records what was typed, pasted or generated.	Pro $12 a month billed yearly, $30 month to month.	Corrections and 100 AI prompts a month. No detection.	Lives inside your editor all day. Detection is a side feature, and Authorship proves how you wrote, not whether what you wrote is new.
SurferWill this page rank on Google, and does it read as AI?	Scores a draft against the pages that already rank for a keyword and suggests what to add. Offers an AI detector and humanizer, and tracks visibility in AI search.	From €49 a month for 120 documents, €99 for 360, billed yearly.	AI Detector and AI Humanizer.	Built to match what already ranks, which is the opposite of saying something new.

Expulp Verdict

What does this piece add beyond what AI already knows and what is already published?

How it works: Breaks the piece into claims and checks each one against what a model would say, what is already online and what others submitted before. Every claim is weighed for credibility and usefulness, and the piece is read both as of its publication date and against today's web.
Pricing: Quick read free. Full verdict one credit: $1 each, 10 for $5, 50 for $20. Plans from $9 a month for 150 credits. Every credit comes with five quick reads. Credits last 90 days.
Free: 3 quick reads a day, 5 with a free account. Anything analysed before is free.
Notes: Shows its reasoning claim by claim, so you can see why. Takes longer than a detector: up to a minute for a quick read, one to two for a verdict. Fiction is still experimental.

GPTZero

Was this written by an AI?

How it works: Reads the whole text and returns a probability that it is AI-written, with sentence highlights. Paid plans add a plagiarism check and a replay of how a document was typed.
Pricing: Premium €9.99 a month for 300,000 words, Professional €19.99 for 500,000, billed yearly.
Free: 10,000 words a month, 10,000 characters per scan.
Notes: Fast and popular with teachers. Rewording a text changes its answer, and it sometimes flags human writing as AI.

Originality.ai

Is this AI-written, and is it copied?

How it works: AI probability and plagiarism matching for the whole text, plus readability and fact-check hints. Scans whole sites and has a Chrome extension that watches writing as it happens.
Pricing: Pro $14.95 a month for 2,000 credits (one credit per 100 words, two with plagiarism); yearly $12.95. Enterprise $179 with API access.
Free: A small daily allowance.
Notes: Made for marketing teams publishing at volume. Like any detector, a paraphrase changes its verdict without changing the content.

Copyscape

Does this text appear somewhere else on the web?

How it works: Matches exact wording against its web index. Copysentry watches your pages for copies every day or week.
Pricing: 3 cents a search for up to 200 words, 1 cent per extra 100 words: about 16 cents for a 1,500-word piece. Copysentry from $4.95 a month.
Free: A limited search by URL.
Notes: The reliable choice for catching copies. It cannot see paraphrase, and it says nothing about ideas.

Turnitin

Does a student's work overlap known sources, and was it AI-written?

How it works: Compares submissions with its database of papers and the web, and adds an AI-writing score for institutions that license it.
Pricing: Sold to schools and universities on quote, not to individuals. Individuals can use iThenticate: $125 per manuscript, without AI detection.
Free: None.
Notes: The standard in education and academic publishing. Its AI score is advisory, and the company says not to act on it alone.

Grammarly

Is this well written, and does it contain AI text or plagiarism?

How it works: A writing assistant for grammar, tone and rewriting. The Pro plan adds a plagiarism checker and an AI detector; Authorship records what was typed, pasted or generated.
Pricing: Pro $12 a month billed yearly, $30 month to month.
Free: Corrections and 100 AI prompts a month. No detection.
Notes: Lives inside your editor all day. Detection is a side feature, and Authorship proves how you wrote, not whether what you wrote is new.

Surfer

Will this page rank on Google, and does it read as AI?

How it works: Scores a draft against the pages that already rank for a keyword and suggests what to add. Offers an AI detector and humanizer, and tracks visibility in AI search.
Pricing: From €49 a month for 120 documents, €99 for 360, billed yearly.
Free: AI Detector and AI Humanizer.
Notes: Built to match what already ranks, which is the opposite of saying something new.

Reading the table

Each of these tools is good at its own question. A detector tells a teacher when to ask a student more questions. Copyscape tells a publisher when a text was lifted. Surfer tells a marketer when a page covers what already ranks. None of them tells a writer or an editor whether a piece says anything that has not been said before. That is the question Verdict was built for. They work well together: a copy check for lifted text, Verdict for whether the rest is worth publishing.

Try a free quick read What Verdict gets right, and where it is weak

One-to-one comparisons

Product names belong to their owners. Descriptions are our reading of each vendor's public pages on 2 November 2026.