Quick links
The tools people arrive here looking for, one click each. Grouped by what you are trying to do. Direct links to the vendor, with the directory entry beside each one for the limits and the date it was last checked.
Check text for AI
Classifier detectors. Free to try, instant, and fallible: run two, expect disagreement, and treat a score as a reason to ask questions rather than as proof.
- Pangrampangram.comFree checker with limitsdetails
- GPTZerogptzero.meFree checkerdetails
- Scribbr AI Detectorscribbr.comFree, no accountdetails
- Copyleaks AI Detectorcopyleaks.comLimited free usedetails
- Originality.aioriginality.aiPaid creditsdetails
- ZeroGPTzerogpt.comFreedetails
- Sapling AI Detectorsapling.aiFree checkerdetails
- Writer AI Content Detectorwriter.comFree for short passagesdetails
- Binocularsarxiv.orgOpen source, run it yourselfdetails
Paraphrase or rewrite text
General rewriting tools for clarity, tone and length. Listed for what they do, not for passing anything.
- QuillBotquillbot.comFree to 125 wordsdetails
- Grammarlygrammarly.comFree tierdetails
- Wordtunewordtune.com10 free rewrites a daydetails
- DeepL Writedeepl.comFree with limitsdetails
- LanguageTool Paraphraserlanguagetool.orgFree with limitsdetails
- Scribbr Paraphrasing Toolscribbr.comFreedetails
- Hemingway Editorhemingwayapp.comFree in the browserdetails
Verify a watermark or provenance
Provider marks and content credentials. Text watermark detection is by application; the Content Credentials tool is open to anyone with a file.
- Content Credentials verify toolcontentcredentials.orgFree, any filedetails
- SynthID for textdeepmind.googleGoogle portal and librarydetails
- synthid-text librarygithub.comOpen sourcedetails
- Claude text watermarkanthropic.comDetection by applicationdetails
- textGrainopenai.comDetection by applicationdetails
Turnitin, for students and teachers
The detector most people are asking about when they search this subject, and the vendor's own explanation of what the percentage means.
- Turnitin AI writing detectionturnitin.comInstitutional licencedetails
- Turnitin detection model guideguides.turnitin.comFree, read this firstdetails
- Turnitin release notesguides.turnitin.comWhat changed and when
Compare detectors and read the research
The neutral scoreboard and the papers that explain why scores disagree.
- RAID benchmarkraid-bench.xyzLeaderboard, open datadetails
- GPT detectors are biased against non-native English writersarxiv.orgThe false positive studydetails
- Can AI-Generated Text be Reliably Detected?arxiv.orgWhy detection is harddetails
- Reducing Risks Posed by Synthetic Contentnist.govNIST overviewdetails
Read the rules
The two laws that now require marks, and the platform policies that restrict removing them.
- EU AI Act, Article 50artificialintelligenceact.euEU, applies from Aug 2, 2026details
- California AI Transparency Act (SB 942, amended by AB 853)leginfo.legislature.ca.govCalifornia, platforms from 2027details
- Anthropic Usage Policyanthropic.comAnthropic usage policydetails
- OpenAI Usage Policiesopenai.comOpenAI usage policiesdetails
About humanizers
Humanizers, the rewriters sold on passing detectors, are listed in the paraphrasers section with their caveats and are not quick-linked here. Nothing on this site tests or ranks evasion. The list is on the paraphrasers page, and the arms race guide explains why last year's results no longer hold.
Questions
Which AI detectors are free?
Pangram, GPTZero, Scribbr, ZeroGPT, Sapling and Writer offer free checks with word or volume limits; Copyleaks has limited free use; Originality.ai is paid. Binoculars is open source and free to run yourself. Free or paid, none is proof on its own.
Is there a tool that checks for a ChatGPT, Claude or Gemini watermark?
Not a public one. Each provider holds its own detector and grants access by application to regulators, researchers, educators and similar organisations. The Content Credentials verify tool checks files for C2PA metadata, which is a different, open system.
Why are humanizers not in the quick links?
Humanizers are rewriters sold on passing detectors. They are listed in the paraphrasers section with their caveats so the directory is complete, but this site does not test, rank or recommend evasion.
How often are these links checked?
Every entry carries the date a person last opened the link and checked the note. The site build date is on every page. Treat anything older than ninety days as possibly stale.