REST API · Plagiarism checker · AI detector

Plagiarism & AI Detection API for your own apps

The Plagiarism Checker Plus API is a plagiarism checker API and AI detection API in one. Send text from your own app, then get a plagiarism score with matching sources and an AI score with per-sentence verdicts back as JSON — the same checks as our web app.

Get an API key Read the API docs
REST + JSONOpenAPI 3.1 specIncluded in every paid plan
How it works

Three calls from text to results

  1. 1

    Create an API key

    In the web app, open Settings › API keys and create a key. It is shown once, then stored only as a hash — keep it on your server.

  2. 2

    Submit text

    POST the text and the checks you want to /scans. You get a scan ID back immediately; the check runs in the background.

  3. 3

    Poll for results

    GET /scans/{id} until the status is completed — typically 30–90 seconds, depending on length. Results arrive per tool as each one finishes.

Endpoints

A small API that does one job well

Every endpoint lives under https://app.plagiarismcheckerplus.com/api/public/v1 and takes your API key as a bearer token: Authorization: Bearer wgk_…

POST/scans
Submit text for checking. Send text and tools (plagiarism, ai_detect or both) and an optional name. Returns 202 straight away with the scan id, word count and words charged.
GET/scans/{id}
Get a scan’s status (pending, processing, completed or failed), progress per tool, and results as each tool finishes. Add ?include_text=true to get the submitted text back.
GET/scans
List your scans, newest first, with page and limit (up to 100 per page).
GET/account
Your plan, words used and remaining this month, purchased word balance, the longest text your plan accepts, and when your allowance resets.
Quick start

Check text for plagiarism and AI with curl

Submit the text with the checks you want, then poll the scan until it completes. The example responses below are shortened.

1. Submit text
curl -X POST https://app.plagiarismcheckerplus.com/api/public/v1/scans \
  -H "Authorization: Bearer $PCP_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "text": "The text you want to check (at least 50 words).",
    "tools": ["plagiarism", "ai_detect"],
    "name": "essay-draft-1"
  }'
HTTP/1.1 202 Accepted

{
  "id": "3f6c1e2a-8b4d-4c9e-9a17-2d5b8f0c7e41",
  "status": "processing",
  "wordCount": 800,
  "wordsCharged": 1600,
  "tools": ["plagiarism", "ai_detect"]
}
2. Poll for results
curl https://app.plagiarismcheckerplus.com/api/public/v1/scans/3f6c1e2a-8b4d-4c9e-9a17-2d5b8f0c7e41 \
  -H "Authorization: Bearer $PCP_API_KEY"
{
  "id": "3f6c1e2a-8b4d-4c9e-9a17-2d5b8f0c7e41",
  "status": "completed",
  "tools": ["plagiarism", "ai_detect"],
  "results": {
    "plagiarism": {
      "score": 12.5,
      "uniqueSources": 2,
      "sources": [
        {
          "url": "https://example.org/article",
          "domain": "example.org",
          "matchPercentage": 8.1,
          "matchedText": "The passage from your text that matched.",
          "excerpt": "Surrounding text from the source page."
        }
      ]
    },
    "aiDetection": {
      "score": 64,
      "summary": "…",
      "sentences": [
        { "text": "A sentence from your text.", "probability": 0.93, "offset": 0, "length": 26 }
      ]
    }
  }
}

Full request and response schemas, error codes, a Node.js example and an interactive console are in the API docs. The raw OpenAPI spec is at openapi.json.

What you get back

Results you can build on

Plagiarism results

A plagiarism score (the percentage of the text matched to sources), the number of unique sources, and for each source its URL, domain, match percentage, the passage from your text that matched, and surrounding text from the source page.

AI detection results

An AI score (the percentage of the text judged AI-generated), a summary, and a verdict for each sentence: a 0–1 probability plus its character offset and length, so you can highlight it in your own UI.

Usage you can check

GET /account returns your plan, words used and remaining this month, purchased balance and the longest text your plan accepts — useful before you submit.
Plans, billing and limits

What to know before you build

Paid plans only

The docs are public and any account can create a key, but API calls need a paid plan. A key on the free plan returns 403 plan_required. Your email address must be verified. See plans.

Billed in words

A scan uses its word count once per tool: 800 words checked for plagiarism and AI uses 1,600 words. Words come from your monthly allowance first, then your purchased balance, and are refunded automatically if a scan can’t be queued.

60 requests per minute per key

Responses carry X-RateLimit-Limit and X-RateLimit-Remaining; over the limit you get 429 with Retry-After. Give each integration its own key (up to 10 active keys) for separate budgets.

50 words minimum

Shorter text returns 400 text_too_short and costs nothing. The maximum length depends on your plan; longer text returns 400 doc_too_long.
Security

Keys and text, handled carefully

Keys are stored only as a hash

A key is shown once, when you create it, and can’t be retrieved again. Keep it on your server, never in browser or mobile code. Revoke a key in Settings › API keys at any time; a revoked key stops working immediately.

Your text is used only for your results

Text you send is used to produce your results and saved to your scan history. We never sell it and never use it to train AI models. Read our privacy policy for details.
No detector is perfect
AI detection gives a likelihood, not proof. It can flag human writing — especially formal or formulaic text — and miss AI text that has been heavily edited. Plagiarism matches include the source text so a person can judge each one. If you build on the API, show results as a starting point for review, not a verdict.
FAQ

API questions

Yes. The Plagiarism Checker Plus API is a REST API that checks text for plagiarism and AI-generated content. You send text to POST /scans and read the results from GET /scans/{id}: a plagiarism score, the number of unique sources, and each matching source with its URL, match percentage, the passage from your text that matched and surrounding text from the source.

Add plagiarism and AI detection to your app

Create a key in the web app, read the docs, and make your first call in minutes. Not a developer? Try the Chrome extension or the Google Docs add-on.

Get an API key Read the API docs

Use of the API is subject to our Terms of Service and Privacy Policy. Questions? Contact us.