Plagiarism Similarity Checker - Free Online AI Detection Tool

Compare two texts side by side and instantly see their overlap percentage with highlighted matching phrases. This local n-gram comparison runs entirely in your browser — no uploads, no sign-up, no external databases. Adjust match sensitivity from High to Low to control how short phrases trigger matches. View exact shared phrases in both documents, plus stats on matched chunks, overlapping words, and longest continuous match.

How to Use

  1. Paste the first text into Text A and the second text into Text B on the side-by-side input panels.
  2. Select your match sensitivity level — High catches short phrases while Low only flags longer matching blocks.
  3. Click the Compare button to calculate the overlap score and see highlighted shared phrases in both documents.
  4. Review the statistics showing matched chunks, overlapping words, and the longest continuous match found.

Key Features

Frequently Asked Questions

Is this a real plagiarism checker?

This tool performs local n-gram text overlap analysis between two documents you paste. It is not connected to any external database or web index, so it identifies shared phrases between your texts but cannot detect content copied from the internet or other sources.

How does match sensitivity work?

The sensitivity setting controls the minimum n-gram length that counts as a match. High (4 words) catches shorter overlapping phrases for more sensitivity, Mid (6 words) balances detection and false positives, and Low (8 words) only flags longer continuous blocks.

Is my text data uploaded anywhere?

All n-gram comparison runs entirely locally in your browser. No text is uploaded to any server. The optional AI paraphrasing suggestions require you to enter your own API key in the AI settings panel, and those requests go directly to your chosen provider.

Can I use this for academic work?

Yes — it helps you identify text overlap between two documents, such as your draft versus a source. However, the tool shows exact shared phrases so you can judge whether matches are legitimate (quotes, common phrasing) or problematic. Use it as a starting point, not a definitive verdict.

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