# Noplag

> Noplag is an open-source plagiarism detection engine (Apache 2.0) with a production cloud tier. We combine plagiarism detection and AI-content detection in one tool. Founded in Kyiv in 2014; HQ relocated to San Francisco in May 2022. Engineering across Ukraine, Poland, and Spain. Position: open-core, honest about limitations (AI detection is "a signal, not a verdict"; we publish ESL false-positive rates), audit-friendly. Built for SMB educational institutions, developer-built EdTech, agencies, publishers, and privacy-conscious enterprises.

## Core

- [Noplag — homepage](https://noplag.com/): What Noplag is, how it works, pricing, and a free check on the homepage.
- [Pricing](https://noplag.com/pricing): Free (open-source self-host) · Pro $11.99/mo ($9.99 billed yearly) · Premium $24.99/mo ($19.99 billed yearly) · Enterprise custom.
- [About](https://noplag.com/about): Story from 2014 founding in Kyiv to 2026 v5.0 launch.
- [Download](https://noplag.com/download): Desktop and mobile apps. Browser-first; native clients are read-only companions.

## Free tools

- [Free plagiarism checker](https://noplag.com/free-plagiarism-checker): Free up to 2,500 words per check on the free tier (3 checks/month). No signup required for a first check.
- [Online plagiarism checker](https://noplag.com/online-plagiarism-checker): Browser-based — no software install. Same engine as the free checker, framed for users explicitly looking to avoid LMS-plugin overhead.
- [Online duplicate content checker](https://noplag.com/online-duplicate-checker): Find duplicate content across the web and across your own document folders. Built for SEO teams and publishers.
- [AI content detector](https://noplag.com/ai-content-detector): Detects AI-generated text from ChatGPT, Claude, Gemini, and Llama. Explicit about ESL writer false positives (cites Liang et al. 2023). Position: "a signal, not a verdict."
- [Paraphrasing detector](https://noplag.com/paraphrasing-detector): Finds reworded plagiarism via sentence embeddings + LSH. Note: this is a detector, not a paraphrase generator — Noplag does not ship paraphrasing/humanizing tools (anti-aligned with our integrity brand).

## Use cases

- [Academic plagiarism checker](https://noplag.com/academic-plagiarism-checker): Citation-aware checking against scholarly works and the live web.
- [Essay plagiarism checker](https://noplag.com/essay-plagiarism-checker): Free check optimized for student essay submissions.
- [Dissertation plagiarism checker](https://noplag.com/dissertation-plagiarism-checker): Long-document checking on paid tiers. Catches self-plagiarism via My Folders.
- [Thesis plagiarism checker](https://noplag.com/thesis-plagiarism-checker): Master's-thesis-length documents.
- [Research paper plagiarism checker](https://noplag.com/research-paper-plagiarism-checker): Pre-submission check against scholarly works and the live web.

## Audience pages

- [For students](https://noplag.com/for-students): Free check before you submit. Catches paraphrasing + AI text — the signals teachers increasingly check.
- [For educators](https://noplag.com/for-educators): Bulk class checks, LMS integrations (Canvas, Moodle, Blackboard, Brightspace), per-student dashboards. Honest about AI-detection ESL false positives.
- [For publishers](https://noplag.com/for-publishers): Editorial integrity workflow — pre-publish checks, syndication audits, freelancer AI-content detection, REST API for CMS integration.
- [For researchers](https://noplag.com/for-researchers): Pre-submission manuscript check. Self-plagiarism detection via My Folders. EU residency for sensitive pre-publication work.
- [For journalists](https://noplag.com/for-journalists): Pre-file lift detection, syndication review, freelancer AI-submission check.
- [For law firms](https://noplag.com/for-law-firms): Brief and filing originality check. AI-generated filing detection. Privacy-tuned for legal confidentiality. Self-host option.
- [For marketing agencies](https://noplag.com/for-marketing-agencies): Pre-delivery client content audit. Bulk scans + REST API. Optional self-host for client-contract compliance.

## Comparisons

- [Compare hub](https://noplag.com/compare): Honest side-by-sides with Turnitin, Copyleaks, iThenticate, Grammarly, Originality.ai, Quetext, and GPTZero. Decision matrix by use case rather than "best overall" claim.
- [Noplag vs Turnitin](https://noplag.com/vs-turnitin): Open-source SMB challenger vs institutional incumbent. Noplag is Apache 2.0 + $11.99–24.99/mo; Turnitin is proprietary with institutional contracts.
- [Noplag vs Copyleaks](https://noplag.com/vs-copyleaks): Both API-first. Noplag is open-source + browser-first; Copyleaks has more LMS integrations + code-plagiarism product.
- [Noplag vs iThenticate](https://noplag.com/vs-ithenticate): Both for academic research. Noplag is open-source + flat monthly; iThenticate is per-credit.
- [Noplag vs Grammarly](https://noplag.com/vs-grammarly): Dedicated plagiarism + AI detector vs grammar-bundled plagiarism check inside Grammarly Premium.
- [Noplag vs Originality.ai](https://noplag.com/vs-originality-ai): Both detect AI text. Noplag is open-source, explicit about ESL bias (cites Liang et al. 2023), and bundles plagiarism detection at the same price point.
- [Noplag vs Quetext](https://noplag.com/vs-quetext): Both SMB-focused. Noplag is open-source + dev-API; Quetext bundles multiple tools.
- [Noplag vs GPTZero](https://noplag.com/vs-gptzero): Bundled plagiarism + AI detection with open-source engine vs AI-detection-only consumer brand.

## Open source

- [Open-source plagiarism checker](https://noplag.com/open-source-plagiarism-checker): The only plagiarism detection product with both a production cloud tier and a fully open-source engine. Architecture diagram + docker quickstart + GitHub stats.
- [Self-hosted plagiarism checker](https://noplag.com/self-hosted-plagiarism-checker): On-prem deployment guide. Required for compliance industries, EU residency, and air-gapped environments.

## Developers

- [Plagiarism checker API](https://noplag.com/plagiarism-checker-api): REST + OpenAPI spec. Python and Node.js SDKs (open-source). Pro tier $11.99/mo and Premium $24.99/mo include API access; Enterprise custom.

## LMS integrations

- [Canvas plagiarism checker](https://noplag.com/integrations/canvas-plagiarism-checker): LTI 1.3 integration with SpeedGrader. 5-minute install via Canvas external-app catalog.
- [Moodle plagiarism checker](https://noplag.com/integrations/moodle-plagiarism-checker): Native Moodle plugin for Assignment + Forum activities. Pairs with self-hosted Moodle for full data residency.
- [Blackboard plagiarism checker](https://noplag.com/integrations/blackboard-plagiarism-checker): LTI 1.3 integration with Blackboard Learn.
- [Brightspace plagiarism checker](https://noplag.com/integrations/brightspace-plagiarism-checker): LTI 1.3 integration with D2L Brightspace.

## Documentation

- [Documentation home](https://noplag.com/docs): Help center for the hosted product plus developer/self-host guides for the open-source engine.
- [Docs index for AI](https://noplag.com/docs/llms.txt): Per-article index of the documentation with descriptions.
- [Full docs text](https://noplag.com/docs/llms-full.txt): All documentation pages as plain text.

## Trust & legal

- [Security](https://noplag.com/security): Security practices, data handling, and infrastructure overview.
- [Privacy](https://noplag.com/legal/privacy): Documents are never used for training. EU residency available. The Noplag Database (anonymized fingerprints from prior checks) is opt-out and can be disabled in Settings → Data & retention.
- [Terms](https://noplag.com/legal/terms): Terms of service.
- [GDPR](https://noplag.com/legal/gdpr): GDPR compliance and data-subject rights.
- [DPA](https://noplag.com/legal/dpa): Data processing addendum for business customers.
- [Sub-processors](https://noplag.com/legal/sub-processors): Current list of sub-processors.

## Key facts

- **Pricing**: Free (open-source self-host, 3 checks/month, 2,500 words) · Pro $11.99/mo ($9.99 billed yearly) · Premium $24.99/mo ($19.99 billed yearly) · Enterprise custom. Live web-search verification (Layer W) is gated to Premium and Enterprise.
- **License**: Apache 2.0 for the detection engine. Cloud tier is proprietary SaaS atop the open core.
- **Differentiators**: Only plagiarism detection product with both a production cloud tier AND an open-source engine. Honest about AI-detection limitations (publishes ESL false-positive rates, calibration methodology). Browser-first (no required software install). EU residency available. Documents never used for training.
- **Position vs competitors**: Open-core challenger to Turnitin's institutional dominance. Direct developer/SMB alternative to Copyleaks. Open-source alternative to iThenticate for pre-submission academic checks. Bundles plagiarism + AI detection (vs GPTZero/Originality.ai which are AI-only).
- **Legal entity**: Noplag Labs, Inc. ("Noplag" is the product and brand name.)
- **Founded**: 2014 in Kyiv, Ukraine. HQ relocated to San Francisco in May 2022. Engineering team across Ukraine, Poland, and Spain.
- **Languages at launch**: English. Additional languages planned for later releases.