Plagiarism Checker API & AI Detection API: Integrate Red Paper™ in Minutes

Introduction

Every modern EdTech platform, learning management system, and content publisher faces the same challenge: how do you automate plagiarism checking and AI content detection at scale without asking users to leave your app? The answer is a plagiarism checker API — a programmable interface that embeds professional-grade detection directly into your workflow.

Red Paper™ at www.checkplagiarism.ai now offers a fully documented RESTful plagiarism detection API that bundles plagiarism scanning and AI detection in every call. Whether you're building a homework-submission portal, a CMS plugin, or a content-QA pipeline, our API delivers 99% accuracy with asynchronous webhook-based processing — and pricing starts at just ₹10 per credit.

In this guide we'll cover how the API works, its endpoints and code samples, how it compares to alternatives like the Copyleaks plagiarism checker API, and how to go from zero to integrated in under 30 minutes.

Why You Need a Plagiarism Checker API

Scale Beyond Manual Checking

Manual copy-paste into a web-based plagiarism checker is fine for a handful of documents. But when your platform processes hundreds or thousands of submissions per day — student assignments, freelancer articles, or user-generated content — only a plagiarism API lets you automate the process end to end.

Keep Users Inside Your Product

Redirecting users to an external plagiarism detector creates friction and breaks the experience. A plagiarism checker API runs silently behind the scenes: your user uploads a document, your back-end calls the API, and the results appear natively in your interface.

Combined Plagiarism + AI Detection in One Call

Separately licensing an AI plagiarism checker and a traditional plagiarism service doubles your cost and complexity. Red Paper's API returns both plagiarism similarity scores and AI content detection results from a single scan — one submission, one credit, two reports delivered via webhook.

Stay Ahead of AI Writing Tools

ChatGPT, Claude, and Gemini are getting better every quarter. To keep your plagiarism detection relevant, you need a provider that updates its models continuously. Red Paper's AI detection API is retrained monthly on the latest AI-model outputs so your integration never goes stale.

Red Paper API: Features & Capabilities

Red Paper's API is designed for developers who need reliable plagiarism detection and AI detection without the overhead of building their own NLP stack. Here's what you get out of the box.

Core Detection Engines

Plagiarism Engine: Cross-references input against 1 billion+ web pages, academic papers, journals, and books. Returns per-sentence match percentage, matched source URLs, and an overall similarity score — everything a robust plagiarism checker should provide.

AI Detection Engine: Identifies content generated by ChatGPT (GPT-3.5 / GPT-4 / GPT-4o), Claude, Gemini, Copilot, Jasper, and 15+ tools. Returns an AI-probability percentage, human vs AI word breakdown, and severity assessment. This is the same AI plagiarism checker technology trusted by 2,000+ institutions — now available as an API.

Supported Input Formats

The plagiarism detection API accepts PDF, DOCX, DOC, TXT, and RTF files via multipart/form-data upload. Simply attach your document as the file field along with a unique scan_id and webhook_url to get started.

Response Format

Every API response is a structured JSON object. Scan results include similarity percentage, identical/minor-changes/paraphrased word counts, AI detection percentage (when enabled), and a downloadable PDF report with highlighted matches and source URLs. Parseable, storable, and ready to render in any front-end.

Webhooks & Async Processing

The API uses fully asynchronous processing with webhook callbacks. Submit the document, receive a scan_id, and get notified via webhook at three stages: credit calculation, scan completion, and PDF report delivery — perfect for non-blocking integration in your plagiarism checking pipeline.

API Endpoints & Quick-Start Guide

Getting started with the plagiarism checker API takes just three steps: get your key, make a request, and parse the response. Below are the primary endpoints and a minimal Python example.

Authentication

Every request requires an API key sent via the Authorization: Api-Key YOUR_API_KEY header. Generate your API key from the Red Paper API Key Management page at www.checkplagiarism.ai/api/key-management.

POST /api/plagcheck/scan — Submit Document for Scanning

This is the primary endpoint for the plagiarism detection API. Upload a file via multipart/form-data with your scan options and webhook URL. The API processes asynchronously and delivers results to your webhook.

# Python Quick-Start — Red Paper Plagiarism Checker API
import requests
import uuid

API_KEY = "your_api_key_here"
ENDPOINT = "https://www.checkplagiarism.ai/api/plagcheck/scan"

scan_id = str(uuid.uuid4())  # Generate a unique scan ID

files = {"file": open("assignment.pdf", "rb")}
data = {
    "scan_id": scan_id,
    "webhook_url": "https://your-server.com/webhook",
    "include_ai": "true",
    "include_paraphrasing": "true",
}

headers = {"Authorization": f"Api-Key {API_KEY}"}

response = requests.post(ENDPOINT, files=files, data=data, headers=headers)
result = response.json()

print("Scan ID:", result["data"]["scan_id"])
print("Status:", result["data"]["status"])  # "pending"
# Results will be delivered to your webhook_url
    

Scan Options & Custom Branding

The submit scan endpoint accepts optional parameters to customise your plagiarism API scan: include_ai, exclude_references, exclude_quotes, include_paraphrasing, min_copied_words, and action (0 = auto-start, 1 = check credits first). You can also pass custom branding fields like custom_logo, title_color, report_title, report_subtitle, submitted_by, and highlight colours (identical_color, minor_changes_color, related_meaning_color, ai_detection_color).

POST /api/plagcheck/reports/{scan_id} — Retrieve Report

After scan completion, call this endpoint to fetch the complete plagiarism detection and AI detection report including similarity percentage, word counts, and scan options.

POST /api/plagcheck/reports/{scan_id}/download — Download Report PDF

Download the full plagiarism report as a branded PDF with highlighted matches and source URLs.

GET /api/plagcheck/reports/{scan_id}/certificate — Download Certificate

Generate and download an originality certificate PDF for the completed scan. This is a public endpoint — no API key required.

POST /api/plagcheck/subscription — Check Credit Balance

Returns your remaining credit balance, allotted credits, and subscription expiry date.

More Code Samples

Full code samples for cURL, Python, JavaScript, PHP, Java, Ruby, and Go are available in our API Documentation. Every example demonstrates both plagiarism checking and AI content detection in a single scan.

AI Detection API: Detect ChatGPT & AI Content

Red Paper's AI detection API is not a bolted-on extra — it's a core part of every scan. When you call the plagiarism endpoint, the response includes a complete AI analysis powered by the same engine that serves our web-based AI plagiarism checker.

What the AI Detection API Returns

The JSON response includes AI detection fields: overall AI percentage, human percentage, AI word count vs human word count, severity level, and an AI probability score. The downloadable PDF report also includes a visual AI detection section. This gives developers everything needed to render a detailed AI content detection report inside their own UI.

Models Detected

Our AI detection API currently identifies output from ChatGPT (all GPT-3.5 and GPT-4 variants), Anthropic Claude, Google Gemini, Microsoft Copilot, Meta Llama, Jasper, Copy.ai, Writesonic, and 10+ other generators. The detection model is retrained monthly so it keeps up with the latest releases.

Handling Paraphrased & Humanized AI Text

Many users run AI output through paraphrasing tools before submission. Red Paper's plagiarism detection API catches semantic-level plagiarism while the AI engine detects residual linguistic fingerprints that survive paraphrasing. Together, the two engines form a safety net that neither can provide alone — a true AI plagiarism checker pipeline.

Accuracy Benchmark: Red Paper vs Competitors

Not every plagiarism checker API delivers the same quality. Here's how Red Paper's API accuracy stacks up against leading alternatives in independent testing.

Red Paper stands out as the most cost-effective plagiarism checker API with the broadest feature set — especially for startups and mid-size EdTech companies that need enterprise accuracy without enterprise budgets.

Use Cases: EdTech, LMS, CMS & Publishers

Learning Management Systems (LMS)

Integrate the plagiarism detection API into Moodle, Canvas, or your custom LMS so every student submission is automatically scanned. Instructors see plagiarism and AI scores right inside the grading view — no extra tabs, no manual copy-paste. This is the API equivalent of what Turnitin charges institutions premium rates for, but with Red Paper's plagiarism checker API free trial and flexible pay-per-call pricing.

Content Management Systems (CMS)

WordPress, Drupal, Ghost — any CMS with a publishing workflow can benefit from a pre-publish plagiarism checker gate. Use the API to block or flag articles with high similarity or AI scores before they go live, protecting your site's SEO and credibility.

EdTech & E-Learning Platforms

Online course platforms, coding bootcamps, and MOOC providers use the plagiarism API to ensure assignment authenticity at scale. Combine with the AI detection API to catch both traditional copy-paste plagiarism and AI-generated shortcuts.

Academic Publishers & Journals

Peer-review portals can embed the plagiarism detection API into their submission pipeline. Manuscripts are scanned automatically, and reviewers receive a report alongside the paper. This dramatically reduces the manual effort of plagiarism detection for editorial teams.

Content Agencies & SEO Teams

Agencies managing dozens of freelancers need to verify originality at scale. Plug the plagiarism checker API into your project-management tool and auto-scan every deliverable. The combined plagiarism + AI content detection ensures nothing AI-generated or copied slips through.

Recruitment & HR Platforms

Companies using written assessments in hiring can integrate the API to verify that candidates haven't used ChatGPT or copied answers. A quick plagiarism detection API call during assessment review maintains the integrity of your hiring process.

API Pricing: Free Trial & Pay-Per-Call

Red Paper's plagiarism checker API follows a developer-friendly pricing model — start free, pay only for what you use, and scale with volume discounts. Each credit covers 250 words of combined plagiarism checking and AI detection at a base price of just ₹10 per credit.

Free API Trial

Sign up and receive complimentary credits to test every endpoint. Build your prototype, validate accuracy, and demo to stakeholders — all before spending a rupee. This is the most generous plagiarism checker API free tier in the market.

Subscription Plans

Choose a plan that fits your volume. Higher tiers unlock bigger discounts automatically:

Every plan includes both plagiarism checking and AI detection — one credit, two reports. International pricing is available in USD for developers outside India.

SAVE50 — Limited Time: 50% OFF Any Purchase

Use coupon code SAVE50 at checkout to get 50% off the base price on any credit purchase. The discount applies directly to the base price — for example, the Popular plan (50 credits) drops from ₹500 to just ₹250. This is a limited-time offer, so grab it while it lasts!

Custom & Enterprise

Need more than 500 credits or custom rate limits? Contact our team for tailored enterprise pricing with dedicated support, priority queue, SLA guarantees, and custom branding on all reports.

Step-by-Step Integration Guide

Step 1 — Create an Account & Get Your API Key

Visit www.checkplagiarism.ai/api/key-management and generate your API key. You'll receive free trial credits immediately. This key authenticates all calls to the plagiarism detection API via the Authorization: Api-Key YOUR_KEY header.

Step 2 — Set Up Your Webhook Endpoint

Create an HTTPS endpoint on your server to receive webhook callbacks. The API sends three events to your webhook: credit_calculation (cost estimate), scan_completed (results ready), and report_ready (PDF available). Any language that handles HTTP POST requests works — Python, Node.js, PHP, Java, Go, Ruby, and more.

Step 3 — Make Your First Scan

Use the /api/plagcheck/scan endpoint to upload a document with your scan_id, webhook_url, and scan options like include_ai. Verify the submission response and confirm that webhook callbacks arrive with plagiarism and AI content detection scores.

Step 4 — Handle Webhook Callbacks

All scanning is asynchronous. The plagiarism API will POST results to your webhook URL at each stage. Use the scan_completed event to get similarity scores and report_ready to get the downloadable PDF report URL.

Step 5 — Render Results in Your UI

Parse the webhook JSON to render similarity percentages, word-level breakdowns, and AI flags inside your application. Use the report download endpoint to fetch the full PDF with highlighted matches — similar to Red Paper's own plagiarism checker interface.

Step 6 — Go Live & Monitor

Top up credits and monitor usage via the API Scans Dashboard. Check your credit balance anytime via the /api/plagcheck/subscription endpoint so your plagiarism detection pipeline never goes down unexpectedly.

Frequently Asked Questions

Conclusion

Building plagiarism and AI detection into your platform shouldn't require months of NLP research or six-figure licensing deals. Red Paper's plagiarism checker API gives you 99 %-accurate dual-engine scanning — plagiarism and AI — via a clean REST interface, with a free API trial to get started and pay-per-call pricing that scales with you.

Whether you're powering a university LMS, a content-marketing pipeline, or a SaaS assessment platform, the plagiarism detection API handles the heavy lifting so you can focus on your product. Combine it with our AI detection API and you have a complete content-integrity layer in a single integration.

Join the growing community of developers who trust Red Paper to embed plagiarism checking and AI content detection into their products. Get your API key, claim your free credits, and ship your integration today.