Free Code Plagiarism Checker API
Fast group similarity checks across 50+ programming languages
Detect code similarity and potential plagiarism with modern, high-accuracy analysis. Create a free account to get your API key and integrate in minutes.
Why Codequiry?
A modern reimagination of code similarity detection, built for today's development landscape.
Since 1997, MOSS (by Stanford) has been a staple for detecting plagiarism in programming courses. Today, with the explosion of open-source code and AI code generators, copying and remixing code extends far beyond classrooms.
We reimagined the concept with modern algorithms tailored for today's code ecosystems. Codequiry's MOSS-style alternative delivers powerful, accurate group similarity detection with key improvements:
Multi-Core Processing
Horizontally scalable processing powered by 20 AMD EPYC™ 9655P servers with 2TB combined RAM for lightning-fast analysis.
50+ Languages
Comprehensive support for all major programming languages with native parsing for accurate detection.
Advanced Analysis
Detects structural and semantic edits including renames, reformatting, and comment manipulation.
AI Detection Layer
Machine-learning algorithms identify AI-generated code patterns across your submissions.
Web-Scale Matching
Search-index layer checks billions of code files in real-time for potential matches across the web.
Simple REST API
Easy-to-integrate REST API with clean JSON results and persistent storage for upgraded keys.
Free API: Use our group similarity scanner at no cost. For web and database checks, upgrade to the standard API to unlock full platform access and management tools.
Upload up to 500 ZIP submissions (50+ languages), each up to 10MB, and compute group similarity across the entire set. For global plagiarism detection—including the public web, GitHub, Stack Overflow, and billions of additional sources—create an account
Quick Start
Everything you need to integrate and start detecting code similarity
API Documentation
Learn how to call the endpoints using your API key
Manage Allowed IPs
Allow up to two IPs per API key (e.g., local and production)
Check Usage
View API key usage and related limits
Upgrade API Key
Remove delays and enable persistent results
Limits: Free users have a 5-minute delay between checks (removed when upgrading). Free results are deleted after 7 days; upgraded keys unlock persistent storage. Want visuals? Create an account to view full web results and interactive dashboards.
Getting Started
Follow these steps to run your first plagiarism check
Create Your Account
Enter billing details and basic information (name, email, role, password). We never sell your data. This information establishes account ownership and lets us provide personalized support.
You can change your account information anytime under "Account Settings" in the dashboard.
Create Your First Folder
From the dashboard home page, create your first folder to organize checks. Click "New Folder" (top right) and name it (minimum 3 characters).
Folders help you organize checks by course, project, or any other grouping that makes sense for your workflow.
Upload Submissions
This step is critical; incorrect uploads can cause incomplete or inaccurate results.
Important Information About File Uploads
Provide one .zip per submission containing only that submission's source code. If you have 10 submissions, upload 10 separate .zip files. A .zip with multiple submissions will be treated as a single submission and will not compare correctly.
Ensure each .zip includes at least one file for the selected language (e.g., at least one .java file for Java). We recommend WinZip or WinRAR for compression.
Start Checking for Plagiarism
When your uploads are ready, click the "Start checking files" button in the Upload/Submissions tab of your check.
Timing depends on file counts, code size, and queue load, but results typically appear instantly or within minutes.
Available Check Types
Choose the type of analysis that fits your needs
Group Similarity (Peer Check)
Compare all submissions against one another to surface localized similarities within your group.
Web Check
Check submissions against billions of sources across the public web, including popular code-sharing and Q&A sites.
Understanding Your Results
Comprehensive visualizations and insights for thorough analysis
Insights Page
The Insights page organizes estimated similarity across peer and web samples, ranking the highest matches first.
- Match Composition: Shows where matches originate (e.g., GitHub) and the relative share of each source
- Overall Variance: Tracks variance between web and group similarity—useful for understanding disparity across larger cohorts
Overview Page
Get a bird's-eye view of group similarity scores for comprehensive analysis.
- Cluster Graph: Visualizes proximity between submissions to identify potential collaboration
- Score Bar Chart: Displays each submission with its highest comparison score
- Similarity Table: Lists all comparisons and similarity scores for detailed review
Results Page
Drill into individual submissions with detailed match highlighting and analysis.
- File Viewer: Browse parsed source files with inline highlighting of matched segments
- Match Explorer: View all matches with similarity scores and source URLs
- Plagiarism Score: Estimated probability based on unoriginality signals
- Source Makeup: Pie chart showing unique vs. similar content composition
Important: All results are estimates based on similarity thresholds. Codequiry does not determine plagiarism; reviewers should examine matches and context before drawing conclusions.
Data Management & Privacy
You remain in full control of your data
Privacy First
Codequiry does not use your files for checking other users' submissions and does not share them with third parties.
Export Your Data
Export and download account-related data anytime from your account settings.
Manage Access
Share your plan with teammates and manage access from your account settings.
Ready to Get Started?
Create your free account today and start detecting code similarity with our powerful API.