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Test scope & comparison notes

These are recorded facts, not a unified ranking. Tested tiers and scope are not consistently recorded. Read pricing with its date and timing with its conditions. Privacy observations reflect visible flows and statements, not a security audit.

Detailed tool comparison
CriterionScribbr

AI content detection

98/100
Seven-aspect task score

Scribbr Free AI Detector, powered by Learneo/QuillBot v7.1.0, evaluated our 90-word benchmark sample in 1.8s (2.0s end-to-end), accurately detecting 100.0% AI probability with sentence-level diagnostic coloration and guest access up to 1,200 words, earning an overall score of 98.

Tested export JSON · Output attached

Historical test · 2026-11-03
Account / tier unconfirmed · Calibrated AI vs human text benchmark (literature master & LLM prose, 780 B) · Output attached

Seven-aspect rationale →
Use tool ↗
QuillBot

AI content detection

97/100
Seven-aspect task score

QuillBot, widely adopted by tens of millions of writers globally, demonstrates outstanding diagnostic precision and rapid turnaround with its AI Content Detector. Against our 90-word benchmark AI sample, the v7.1.0 cloud engine completed inference in 1.03s, delivering a calibrated 100.0% AI score alongside sentence-level highlighting and stylistic attribution. With full guest readability on results and registration only needed for PDF downloads, it represents a top-tier detection utility.

Tested export JSON · Output attached

Historical test · 2026-11-03
Account / tier unconfirmed · Calibrated AI vs human text benchmark (literature master & LLM prose, 780 B) · Output attached

Seven-aspect rationale →
Use tool ↗
Pricing & rules
Pricing plans

Scribbr free sign-up-free tools and pay-per-check plagiarism report pricing model · 2026-10-31

Plan · source date
Monthly / one-time
Annual bill / period
Quota & limits
Free Tools2026-10-31 ↗
Free
Free
Free Unlimited free AI detection without sign-up (up to 1,200 words/check), basic plagiarism match overview, citation generator

Basic AI content detection and citation generation

Small Document (Per Check)2026-10-31 ↗
USD 19.95 · one-time payment
Usage / one-time
Usage / one-time Full plagiarism report for up to 7,499 words, Turnitin database comparison, self-plagiarism check, AI highlights

Turnitin plagiarism check and AI content analysis

Regular Document (Per Check)2026-10-31 ↗
USD 29.95 · one-time payment
Usage / one-time
Usage / one-time Full plagiarism report for 7,500 to 49,999 words (dissertations/theses/journal submissions)

Academic plagiarism check for regular manuscripts and theses

Large Document (Per Check)2026-10-31 ↗
USD 39.95 · one-time payment
Usage / one-time
Usage / one-time Full plagiarism report for 50,000+ words large dissertations and manuscripts

Academic plagiarism check for extensive monographs and dissertations

4 plan / billing-period records, all listed; — means that period is not recorded.

AI detector and citation tools are 100% free with no sign-up; premium plagiarism check is billed per document without recurring subscription: Small $19.95, Regular $29.95, Large $39.95.

Cancellation, sources & verification record

Cancellation and refund terms unverified

Scribbr Plagiarism Checker & Pricing Page ↗ · 2026-10-31 Capture 1 ↗

QuillBot Free and Premium annual pricing structure · 2026-10-31

Plan · source date
Monthly / one-time
Annual bill / period
Quota & limits
USD 0/month
—
Monthly Paraphrase up to 100 words in 2 modes, basic grammar fixes and limited AI detection

Text rewriting, basic grammar proofreading, summarizer, citation generator

Premium (Annual)2026-10-31 ↗
—
Annual price not verified
Annual Unlimited words paraphrased, all 9 modes, full AI Humanizer, 25k words/mo plagiarism checks, full AI Detector

Unlimited words, advanced suggestions, tone analysis, faster processing;Displays only equivalent $8.33 USD/mo billed annually without explicit annual total

2 plan / billing-period records, all listed; — means that period is not recorded.

Annual tier displays $8.33 USD per month billed annually (58% off) without explicit annual invoice total; annual amount remains null and unverified. Free tier is permanently free with 100-word limit.

Verification has gaps; unknown prices and quotas are not inferred.

Cancellation, sources & verification record

Cancellation and refund terms unverified

QuillBot Premium Official Pricing Page ↗ · 2026-10-31 Capture 1 ↗

Task quality
Measured fixture results

AI probability: 100% · Human probability: 0% · Classification label: AI-generated · Confidence calibrated: Yes

AI probability: 100% · Human probability: 0% · Classification label: AI-generated · Confidence calibrated: Yes

Fixture findings

Accurately diagnosed 100.0% AI probability and 0% human probability matching ground truth, providing full sentence-level coloration breakdown.

Exceptional benchmark performance: 100.0% AI probability detection matching ground truth, complete with sentence attribution and style trigger analysis in just 1.03s.

Result & output evidence
Delivery capabilities
Recorded export specifications

JSON · Output attached · Check watermark record

JSON · Output attached · Check watermark record

Watermark observation

Not verified

Not verified

Batch & API

Not verified

Not verified

Speed & reliability
Timing observation

Network-observed server wait: 1.8s · End-to-end reference: 2s

Network-observed server wait: 1.03s · End-to-end reference: 1.03s

Interaction experience
Account requirements

Not verified

Not verified

Manual adjustment

Not verified

Not verified

Background & reputation
Service lifecycle notice

Not verified

Not verified

Operator

Scribbr B.V. (Learneo, Inc.)

Learneo, Inc. (Quillbot Division)

Engineering & privacy
Processing location

Uploaded for cloud processing

Processing location unconfirmed

Retention statement

Explicit retention period unconfirmed; inspect policy record

Explicit retention period unconfirmed; inspect policy record

Benchmark evidence preview

Open original ↗