High similarity
Matched text is linked to its source and character range.
Plagiarism Checker APISource matching your reviewers can inspect.
Scan text against web sources and receive a plagiarism score, matched source URLs, highlighted character ranges, and review-ready statistics.
Input
37 words
The Eiffel Tower is a wrought-iron lattice tower on the Champ de Mars in Paris, France. It is named after the engineer Gustave Eiffel, whose company designed and built the tower from 1887 to 1889.
Scan result
- Result 99% match
- Sources checked 24
- Matched words 34
- Sources returned 1
Source
en.wikipedia.org/wiki/Eiffel_Tower
Input
37 words
curl -X POST https://developer-portal.walterwrites.ai/api/plagiarism/scan/
-H "Content-Type: application/json"
-H "X-API-Key: YOUR_API_KEY"
-d '{
"content": "The Eiffel Tower is a wrought-iron lattice tower on the Champ de Mars in Paris, France. It is named after the engineer Gustave Eiffel, whose company designed and built the tower from 1887 to 1889."
}'
Output
"status": "success",
"plagiarism_score": 0.99,
"verdict": "severe_plagiarism",
"sources": [
{
"url": "https://en.wikipedia.org/wiki/Eiffel_Tower",
"similarity_score": 0.97,
"matched_word_count": 34
}
],
"stats": { "word_count": 37, "sources_checked": 24, "matched_word_count": 34 },
"credits_remaining": 1998Build source review into any content workflow.
A synchronous scan with matched sources, stable character ranges, and explicit similarity data for human review.
Matched source URLs
Return source titles, domains, URLs, similarity scores, and matched-word counts.
Highlight-ready ranges
Map every returned start and end offset back to the text exactly as submitted.
Review-friendly verdicts
Use documented score bands as workflow labels, then keep the final decision with a reviewer.
Detailed scan statistics
Receive word, character, sentence, source-count, and processing-time details.
Safe retries
Use an idempotency key to avoid duplicate scans and duplicate charges during retries.
Flat scan pricing
Each completed scan costs 2 credits regardless of text length.
Pair source reviewwith the rest of Walter.
Use one developer portal and scoped API keys for humanization, AI text detection, grammar correction, plagiarism scanning, and AI image detection.
AI Detector API
LiveAnalyze text for AI-generated content with confidence scores and sentence-level details.
AI Humanizer API
LiveTransform AI-generated text into natural, human-like content through a documented REST endpoint.
AI Voice Detector API
Coming soonAudio detection is planned for a future Walter API release.
Plagiarism Checker API
LiveScan text against web sources and return a score, matched URLs, and highlighted character ranges.
Grammar Checker API
LiveCorrect grammar, spelling, and punctuation and return corrected text plus a complete word-level diff.
AI Image Detector API
LiveUpload an image and receive a real, fake, or inpainting verdict with confidence and per-class probabilities.
Start free. One credit pool, every API.
Each plagiarism scan costs a flat 2 credits regardless of text length. Failed scans are refunded automatically.
Need enterprise pricing?
Talk to us about higher-volume workloads and enterprise deployment requirements.
Frequently asked questions.
Documented answers about the endpoint, response, limits, billing, and safe production use.
Is the Walter Plagiarism Checker API live?
Yes. Send a POST request to /api/plagiarism/scan/ with an API key that has the plagiarism_checker scope.
What does the Plagiarism Checker API return?
It returns a 0 to 1 plagiarism score, a verdict, a summary, matched sources, highlighted character ranges, scan statistics, execution time, and the remaining credit balance.
Does a returned match prove plagiarism?
No. The API reports source similarity for review. Quotations, citations, templates, common phrasing, and licensed material can create legitimate overlap, so a person should inspect the matched passage and source.
What are the request limits?
Text must contain at least 50 characters and may contain up to 25,000 words. Word counting is script-aware.
How is plagiarism scanning billed?
Every completed scan costs a flat 2 credits regardless of text length. Failed scans are refunded automatically.
How should retries be handled?
Send an Idempotency-Key header. Reusing the same key with the same text within five minutes returns the original response without another scan or charge.
Ship your first Plagiarism Checker API request.
Create an API key with the required scope, follow the documented request format, and keep the returned evidence in your existing review workflow.
Developer resources.
From the blog
Latest Research & Insights
Guides, comparisons and practical advice from Walter.
View all-
How to Humanize AI Text Inside Claude
One prompt. The whole content workflow. Walter’s MCP connector brings humanization, detection, and batch processing directly into Claude.…
Read more -
ChatGPT vs ChatGPT Plus: My Real Experience After Using Both Every Day
One of the most common questions I get as a heavy AI user is the old “ChatGPT vs…
Read more -
How Does Content Get Flagged for AI in Essays
Ever wondered why your essay suddenly gets flagged as AI? It can be stressful for students, marketers, and…
Read more
