PaperProof searches the live web and compares your document word-by-word — the same shingle-matching technique institution-grade checkers use — then gives you a similarity report with every matched passage highlighted and linked to its source. And unlike anyone else: your documents are stored in your own database.
No software to install, no account password to remember — sign in with Google or Microsoft and you're one minute away from your first similarity report.
Paste your text or upload a .txt / .docx file up to 128 MB — from a one-page essay to a 700-page thesis or a book-length manuscript. The live word counter shows your length against your plan's limit as you type.
Fingerprint phrases from your document are searched across DuckDuckGo, Mojeek, Bing and Wikipedia (Google too, when configured). Candidate pages are fetched and compared word-by-word using 7-word shingle matching — the same technique institution-grade checkers use.
An overall similarity score, every matched passage highlighted in your document, and a source list linking to each match — including your own previous submissions. Print it or save it as PDF in one click.
Everything below is live today on the free plan. No watered-down reports, no paywalled source list.
One number that tells you where you stand: green under 15%, amber under 40%, red above — with a plain-language verdict.
Every matching run of 7+ words is highlighted directly in your document, color-coded by source.
Each match links to the live web page — or the previous submission of yours — that it came from.
Your document's fingerprint phrases are searched on multiple independent engines, so one bad index can't hide a match.
Every new scan is compared against your previous submissions — catch accidental self-plagiarism before reviewers do.
BYOK: scans are saved to the database you connected (Turso, TiDB, D1 or CockroachDB) with automatic failover.
One click to print or save your similarity report as PDF — perfect for submitting with assignments.
Delete any scan with one click. Disconnect your database and nothing of yours remains with us.
Overall similarity, per-source percentages, and your document with matched passages highlighted — this is an illustration. Run your first scan →
The same core technique as the big names — built for individuals, priced for students, and private by design.
| PaperProof | Checker A¹ | Checker B¹ | Checker C¹ | |
|---|---|---|---|---|
| Made for | Students & individual writers | Universities & institutions only | Teams & enterprises | General writing |
| Price for individuals | Free · from $7.99 | Not sold to individuals¹ | From ~$10.99/mo | From ~$12/mo |
| Free scans | 5 every day, forever | — | Trial only | — |
| Similarity score with % | ✓ | ✓ | ✓ | ✗ (style checks only) |
| Matched passages highlighted | ✓ | ✓ | ✓ | ✗ |
| Sources listed & linked | ✓ | ✓ | ✓ | ✗ |
| Compares your previous submissions | ✓ | ✓ | ✗ | ✗ |
| Big-document support | 128 MB files · up to 2.5M words | ✓ | ✓ | ✗ |
| Where your documents are stored | Your own database (BYOK) | Vendor servers | Vendor servers | Vendor servers |
| Sign-in | Google or Microsoft — 1 minute | School SSO only | Email & password | Google / email |
¹ Anonymous capability scorecard — three widely used commercial checkers (an institution-only market leader, an enterprise team checker, and a general writing assistant). Details reflect publicly listed plans as of Sep 2026 and may change — compare capabilities, not logos.
Start free — upgrade when your documents get longer. Secure checkout via Gumroad, instant email delivery.
🎟️ Already bought? Activate your licence key → — it's in your Gumroad receipt email.
💳 Checkout is handled securely by Gumroad — card, PayPal & Apple Pay accepted. Your licence key arrives by email within minutes. Paste it under Billing & Account → Activate a licence (or the 🎟️ box on the Scan page) and your plan upgrades instantly — Institute, School & Campus keys also create your organisation account automatically. Buying for a class with a purchase order? Email support@clickkitfree.com. Your documents stay in your own database on every plan.
The score is the percentage of your words that appear in runs of 7+ consecutive matching words found on public web pages or in your previous submissions. Properly paraphrased text and short common phrases are not flagged — so a low score means your writing is genuinely original, and a high score points you straight at the passages you should rework or cite.
Same core technique — shingle (n-gram) matching against the web and a submission repository — but built for individuals: you don't need an institution to get in, you get a real free tier, and your documents are stored in your own database instead of a vendor's repository. Institution-only checkers are licensed to universities; PaperProof is the checker you can actually use yourself, before you submit.
In the database you connected — Turso, TiDB, Cloudflare D1 or CockroachDB — not on our servers. Your database credentials are AES-256 encrypted in our vault, and we keep zero copies of your documents. If you disconnect your database, nothing of yours remains with us. This is the BYOK ("bring your own key/database") model — unique among plagiarism checkers.
No. The "previous submissions" comparison runs only against your own earlier scans inside your own database — it exists so you can catch accidental self-plagiarism. Your documents are never shown to, or matched for, other users.
.txt and .docx files up to 128 MB — enough for 700-page theses and book-length manuscripts — or paste any text directly (minimum 40 words). Words per scan follow your plan: 15,000 on Free, 75,000 on Premium, 200,000 on Pro, up to 2.5 million words on the Institute plans. For PDFs, copy-paste the text — direct PDF upload is on our roadmap.
Essays typically take 10–25 seconds. We run real searches across multiple engines and fetch candidate pages, so book-length documents (hundreds of thousands of words) can take a few minutes — the page shows live progress while it works, and the full report opens automatically when it's done.
5 scans every day, forever, up to 15,000 words each — no credit card, no trial countdown. Need more? Premium ($7.99) raises it to 30 scans/day and 75,000 words; Pro ($19.99) to 75/day and 200,000 words; the Institute plans go up to 1,000 scans/day and 2.5 million words per scan. See pricing above — your licence key activates the plan instantly after purchase.
Yes — open My Scans and hit the 🗑 button on any scan; the scan, its matches and its text are removed from your database immediately. You can also remove the whole database connection at any time in My Databases.
Sign in with Google or Microsoft — no password to remember — connect a free database, and get your similarity report before your coffee cools.
Check my paper — free →