Privacy policy
Last updated October 23, 2026. plagiarism.ink is run by B Klug and has been online since 2002. This page explains what the site collects, why, who else handles it, and how long it is kept.
The text you check
- Your papers are not stored. The text you paste, or the Word or PDF file you upload to Premium, is used to run your check and is not saved to a database or added to any collection of papers. An uploaded file is converted to text and deleted straight away.
- Web search. To look for matches, the site sends short passages from your text to a web-search provider (currently Serper, which searches Google; Google's own search service is the backup).
- AI-writing check. To estimate whether text was written by AI, the site sends the text (up to roughly the first 12,000 characters) to Anthropic's Claude API, which returns an estimate.
- Short-term caches. So the same check is not repeated, results are kept for a short time, filed under a fingerprint of the text rather than the text itself: search results for up to 3 days, AI results for up to 7 days. An AI result can include a few short phrases quoted from the text as evidence.
Accounts and payments
- Premium accounts: your name, email address and password, and the IP address you signed up from.
- Payments are handled by Stripe. Your card details go straight to Stripe; plagiarism.ink never sees or stores your card number. The site keeps Stripe's customer and subscription references and your subscription's status.
- Usage counts: the number of free checks made from each IP address each day (for the free daily limit) and the number of checks each Premium account makes each month (for the plan's monthly allowance).
- Country: the site looks up the country of your IP address in a copy of MaxMind's GeoLite2 database kept on the server, to apply the free limits. That lookup does not leave the server.
Email is sent through Mailgun: account messages (welcome, password reset, payment problems) and, now and then, news for past customers. Every newsletter-style email has an unsubscribe link. If you paid for this site in the past, we may email you a small number of times about what is new or about an offer to come back, from B Klug at the address on those emails. Every one of them has a one-click unsubscribe link, an address that unsubscribes goes on a permanent do-not-mail list, and the email says where your address came from (you were a customer). Mailgun tells the site when a message bounces or is marked as spam, so that address is not mailed again.
Cookies and analytics
The site uses Google Analytics, which sets cookies, to count visits and see which pages are used. The site's own cookies remember how many free checks you have used, which version of a page you were shown, where you came from and whether you use Premium. The account pages use a session cookie to keep you logged in.
Who else handles your information
Stripe (payments), Mailgun (email), Anthropic (the AI-writing check), Serper and Google (web search), Google Analytics (visit counts) and DreamHost (hosting, including the server's access logs). Each handles it to provide its part of the service. plagiarism.ink does not sell or rent your information to anyone.
How long it is kept
Account and billing records are kept while you have an account and afterwards as billing records. Usage counts are kept as records of use. Cached results expire as described above.
Your choices
- Use the unsubscribe link in any newsletter-style email.
- Email bklug@plagiarism.ink to see, correct or delete the information held about your account.
- You can block or delete cookies in your browser; the free checker still works, but its daily count may reset.
Children
plagiarism.ink is for teachers, students and writers. It is not directed at children under 13 and does not knowingly collect personal information from them.
Changes
If this policy changes, the new version will be posted here with a new date.
Contact
B Klug, bklug@plagiarism.ink. See also the terms of service and the refund and cancellation policy.