How the tools you already know compare
What each tool costs, what it limits and what it says about itself, read from the vendor's own pages with the date we read them. Where a vendor publishes an accuracy figure, we report it as their claim and keep it apart from ours, because nobody outside the vendor can see the texts it was measured on.
- Textlume vs GPTZero
GPTZero alternative
An AI detector for schools and writers, with writing replay, a plagiarism check and classroom integrations.
- Free check
- GPTZeroUp to 10,000 characters, no account
- Textlume250 words, 1 check a day
- Detection languages
- GPTZero5 listed as fully supported
- Textlume13 calibrated
- Textlume vs QuillBot
QuillBot alternative
A writing suite led by its paraphraser, with grammar, plagiarism, AI detection, humanizer and summary tools in one Premium plan.
- Free paraphrasing
- QuillBotUp to 100 words, 2 modes
- TextlumeStandard and Fluency modes, 1 run a day
- Free AI detection
- QuillBotLimited access
- Textlume250 words, 1 check a day
- Textlume vs Grammarly
Grammarly AI detector explained
A writing assistant for grammar, tone and rewrites, with an AI detector, a humanizer, a plagiarism checker and Authorship.
- AI detector
- GrammarlyFree on the web, built into Pro
- TextlumeFree daily check, more words on paid plans
- Result
- GrammarlyShare of text that looks AI-written
- TextlumeScore with range, confidence and sentence marks
- Textlume vs Turnitin
Turnitin AI detection explained
Similarity checking and AI writing detection sold to schools, universities and publishers, read by instructors.
- Who can use it
- TurnitinInstitutions only
- TextlumeAnyone, with a free daily check
- Low scores
- TurnitinUnder 20% shown as an asterisk
- TextlumeAlways shown, with a range
All comparisons
| Tool | Free | Paid from | Plagiarism check |
|---|---|---|---|
| Textlume | One run per day on each word-limited tool, with no account and no card. | 6.99 USD a month billed yearly, or 9.99 USD month to month, for 10,000 humanizer words, 10,000 paraphraser words and 50,000 AI detector words a month. | Coming soon |
| GPTZero | Scans of up to 10,000 characters without an account. Longer scans need a free account. | Shown in the visitor's local currency. Yearly billing is marked as a 45% saving. | Sold as Plagiarism Check, listed in its product menu. |
| QuillBot | Paraphrasing up to 100 words in 2 modes, basic grammar fixes, a limited AI detector and humanizer, summaries up to 1,200 words. | Premium at $4.17 USD a month, billed annually, on the plan page we read. | Included in Premium, 25,000 words a month. |
| Grammarly | A free AI detector on its website. The free plan covers spelling, grammar and tone, with 100 AI prompts a month. | Pro at $12 USD a month billed yearly ($144 a year), or $30 USD month to month. | In Pro, checked against billions of web pages. |
| Turnitin | None for individuals. Students reach it through their institution's licence. | No public price. Sold to institutions. | Similarity Report against Turnitin's own database. |
How we work
Each text language the detector reads has its own calibration. A text in any other language gets no score, only a note that the language is not calibrated.
Our accuracy page lists how often human texts were flagged in a held-out test, per language, including writing by non-native speakers, with every sample size.
Every reading shows a score with a range, a confidence rating and a mark on each sentence. It is a probability, never proof.
Weak spots are on the accuracy page too: French, and texts where a model continues a human opening. Very short texts always get a low confidence rating.