Duplichecker

What is Duplichecker?

Duplichecker is a long-running web-based plagiarism checker that compares submitted text against a large index of web pages, publications, and academic sources to flag exact and paraphrased matches. A companion AI Content Detector estimates whether text was written by a human or a model like GPT-4, giving a percentage breakdown alongside the plagiarism report.

Both tools are usable for free with word-count limits, and paid plans raise the per-search word limit, add bulk document checking (1,000+ files at once), URL exclusion, and API access for developers who want to embed the checker into their own products.

Key features

• Plagiarism checker compares text against web pages, publications, and academic sources
• Detects paraphrased or reworded plagiarism, not just exact matches
• Free AI content detector flags GPT-3/GPT-4-style generated text
• Bulk checking of 1,000+ documents at once on paid plans
• Downloadable PDF/DOCX plagiarism reports and certificates
• Plagiarism-checker API for integrating detection into other applications

How to get started

1. Paste text or upload a document (DOC, PDF, TXT, and more)
2. Run the plagiarism scan or switch to the AI Content Detector tab
3. Review highlighted matches and the originality/AI score
4. Download a report or certificate if needed
5. Upgrade to a paid plan for higher word limits or bulk/API access

Duplichecker pricing

Duplichecker's core plagiarism and AI checkers are free with daily word limits. Paid plans scale from about $9.99/month for a small word allowance up to enterprise tiers near $2,000/month or $150+/year, adding more searches, higher word counts, extra user seats, and API access.

Our take: One of the few plagiarism checkers that bundles a genuinely free, no-signup AI-content detector alongside its plagiarism scan, rather than gating AI detection behind a paywall.

Prices verified 2026-09. Plans change often — confirm on the official site above before you buy.

Use cases

• Students checking an essay for accidental plagiarism before submission
• Teachers verifying whether student writing was AI-generated
• Content teams screening freelance articles for originality before publishing
• Developers embedding plagiarism checking into their own app via the API

Duplichecker vs. alternatives

FAQ

Is Duplichecker free to use?

Duplichecker's plans: Free; paid plans from $9.99/mo. Pricing and free-tier limits change over time, so check the official site above for the latest details.

What is Duplichecker used for?

Free online plagiarism and AI-content checker that scans text against billions of web pages and academic sources.

Who is Duplichecker best for?

Duplichecker is a good fit for students checking an essay for accidental plagiarism before submission, or teachers verifying whether student writing was AI-generated.

What are the alternatives to Duplichecker?

Commonly compared alternatives include Copyleaks, GPTZero, and Scribbr, see the comparison above for how they differ.

How much does Duplichecker cost?

Duplichecker's plagiarism and AI checkers are free to use with daily limits. Paid plans start around $9.99/month for expanded word counts and scale up through Pro and Enterprise tiers priced by search volume, seats, and API access.