Code plagiarism detection
API, reimagined.
The Codequiry API is the production-ready MOSS alternative educators and engineering teams use to detect source code plagiarism across 65+ programming languages. JSON responses, web-scale matching against GitHub & Stack Overflow, and Zeus™ Hyper anti-obfuscation — everything Stanford MOSS doesn't deliver.
The code plagiarism API built for production
Stanford MOSS hasn't changed since 1994. Codequiry was rebuilt from scratch with modern infrastructure, web-scale matching, and an API that drops into any pipeline.
Zeus™ Hyper anti-obfuscation engine
Six-dimensional semantic analysis reads code meaning, not just syntax — resilient to variable renaming, statement reordering, formatting tricks, and AI-paraphrased solutions that fool MOSS, JPlag, and DoloS.
Web-scale matching
Scan billions of indexed sources — GitHub, Stack Overflow, LeetCode, forums, and code archives. Catch what offline tools cannot.
Clean JSON REST API
Structured similarity scores, matched ranges, and source URLs — parse in any language, store in any database, automate any workflow.
Sub-2-minute results
Horizontally scaled GPU + CPU workers process 100+ submissions in parallel — up to 50× faster than single-threaded MOSS.
SDKs, webhooks & CI/CD-ready
Official SDKs for Node.js, Python, PHP, and Java. Signed webhooks for async result delivery. Drop-in integrations for Canvas, Blackboard, Moodle, GitHub Actions, GitLab CI, and Jenkins — built for the modern automated grading and code-review pipeline.
What is source code plagiarism — and how does an API detect it?
Source code plagiarism occurs when programmers copy, modify, or disguise code from other sources without proper attribution. In academic settings, this includes students copying homework assignments, sharing solutions, or using code from GitHub, Stack Overflow, or online tutorials without permission.
Code plagiarism detection tools analyze source code to identify similarities between submissions. Unlike text plagiarism checkers, code plagiarism detectors must understand programming language syntax, variable naming, code structure, and algorithmic patterns to accurately identify copied code — even when it has been modified.
Common code obfuscation techniques include renaming variables and functions, reordering statements, adding dead code, changing formatting, and restructuring loops. Advanced plagiarism detection systems like Codequiry's Zeus™ Hyper can detect these modifications by analyzing semantic meaning rather than just syntax.
What is Stanford MOSS?
MOSS (Measure of Software Similarity) is a free code plagiarism detection system developed at Stanford University by Alex Aiken. Since 1994, MOSS has been the de facto standard for detecting copying in programming assignments.
MOSS works by converting source code into a fingerprint using a technique called "winnowing" and comparing fingerprints to find similarities. It was an important step forward when it launched, but the approach has known limitations today:
- HTML-only results — no JSON API for automation
- Offline only — doesn't check web sources
- Basic obfuscation detection — easily fooled
- Limited language support — missing modern languages
- No webhooks or SDKs — manual process only
Why educators & engineering teams switch from Stanford MOSS to Codequiry
MOSS pioneered fingerprint-based detection in 1994. Thirty years later, modern code plagiarism detection needs different infrastructure — APIs, web matching, anti-obfuscation, and webhooks.
MOSS Limitations
- Returns HTML pages, not JSON data
- Only compares uploaded files — no web search
- Basic fingerprinting easily fooled by renaming
- Email-based submission system
- No API, SDKs, or webhooks
- Single-threaded, slow processing
- Limited to ~25 programming languages
Codequiry Advantages
- Clean JSON API responses
- Web-scale matching (GitHub, StackOverflow, etc.)
- Zeus™ Hyper anti-obfuscation
- REST API with instant responses
- SDKs for Node, Python, PHP, Java
- Parallel processing — 50x faster
- 65+ programming languages supported
Perfect For
- Universities: CS departments, academic integrity
- Bootcamps: Automated homework checking
- Contests: Hackathon & competition judging
- Hiring: Technical interview validation
- Enterprise: IP protection & code audits
- CI/CD: Automated PR checking
The honest code plagiarism API comparison
A side-by-side look at what each source code similarity tool actually ships — not what the marketing pages claim.
| Capability | Codequiry | Stanford MOSS | JPlag | DoloS |
|---|---|---|---|---|
| JSON API Responses | Yes | HTML only | Partial | Partial |
| Web & Repository Matching | Yes | Offline | Offline | Offline |
| Anti-Obfuscation Detection | Advanced | Basic | Basic | Basic |
| SDKs & Webhooks | Full | None | Limited | Limited |
| 65+ Language Support | Yes | Some | Some | Some |
| Unlimited Plans Available | $5k/mo | Limits | Limits | Limits |
Integrate code plagiarism detection in minutes
Four REST calls — create, upload, start, and get results. Authenticated with a single API key, results returned as structured JSON. No XML, no HTML scraping, no waiting on email.
const response = await fetch('https://codequiry.com/api/v1/check/create', { method: 'POST', headers: { 'Accept': 'application/json', 'apikey': process.env.CODEQUIRY_API_KEY }, body: JSON.stringify({ name: 'Assignment 1', language: 'python' }) }); const { check_id } = await response.json(); // Upload files, start check, get JSON results...
Source code plagiarism detection for 65+ programming languages
From Python homework and Java capstones to Rust, Go, Swift, and Solidity — the Codequiry API understands them all, with automatic language detection for mixed-language projects.
Python
Java
JavaScript
C / C++
Rust
Go
Swift
Ruby
Also supported: TypeScript, Kotlin, Scala, PHP, C#, MATLAB, R, Perl, Haskell, OCaml, Erlang, Elixir, Lua, Dart, Julia, Fortran, COBOL, Assembly, SQL, Shell/Bash, PowerShell, and 30+ more.
Where teams ship Codequiry's plagiarism API
From university CS departments to enterprise code audits — real-world deployments of source code similarity detection at scale.
Academic Integrity in CS Education
Computer Science professors use code plagiarism detection to identify copied programming assignments, shared homework solutions, and code from online sources. Codequiry integrates with LMS platforms like Canvas, Blackboard, and Moodle to automate the checking process.
Programming Contest Validation
Hackathons, coding competitions, and online judges use source code similarity detection to ensure submissions are original. Codequiry's web matching catches participants who copy solutions from GitHub, LeetCode, or previous contest archives.
Technical Interview Screening
Hiring platforms integrate code plagiarism APIs to validate take-home coding tests and live coding challenges. Detect candidates who copy solutions from the web or share answers between interview rounds.
Enterprise IP Protection
Legal and security teams audit codebases to identify copied code, license violations, and potential IP theft. Codequiry helps enterprises protect proprietary algorithms and detect unauthorized code reuse in contractor deliverables.
Bootcamp & MOOC Assessment
Coding bootcamps and online learning platforms ensure students complete assignments independently. Automated plagiarism detection at scale — check thousands of submissions per week without manual review.
CI/CD Pipeline Integration
DevOps teams add code similarity checks to pull request workflows. Automatically flag suspicious commits, detect accidental license violations, and ensure code originality before merging to main branches.
MOSS alternative & code plagiarism API — FAQ
What is the best Stanford MOSS alternative?
Codequiry is the leading MOSS alternative for code plagiarism detection. Unlike MOSS, Codequiry provides JSON API responses, web-scale matching, anti-obfuscation detection via Zeus™ Hyper, and support for 65+ programming languages. It's designed for modern workflows with SDKs and webhooks.
How does source code plagiarism detection work?
Source code plagiarism detection works by tokenizing code into structural patterns, then comparing these patterns across submissions. Codequiry's Zeus™ Hyper uses 6-dimensional semantic analysis to understand code meaning — detecting plagiarism even when variables are renamed, code is reformatted, or statements are reordered.
Is this Stanford's MOSS service?
No. Codequiry is an independent alternative to Stanford MOSS, built from scratch with modern technology. While MOSS was pioneering in 1994, Codequiry offers significant improvements: JSON APIs, web matching, advanced anti-obfuscation, webhooks, and 65+ language support.
What programming languages are supported?
Codequiry supports 65+ programming languages including Python, Java, C/C++, JavaScript, TypeScript, Go, Rust, Swift, Kotlin, Ruby, PHP, C#, Scala, MATLAB, R, Haskell, and many more. Language auto-detection is included for mixed-language projects.
How accurate is code plagiarism detection?
Codequiry achieves 95%+ accuracy in detecting code similarities. Our Zeus™ Hyper technology is designed to catch sophisticated obfuscation techniques including variable renaming, code reordering, dead code insertion, formatting changes, and comment modifications.
Can I detect code copied from GitHub or Stack Overflow?
Yes. Unlike MOSS and other offline tools, Codequiry includes web-scale matching that searches billions of indexed sources including GitHub repositories, Stack Overflow answers, online tutorials, forum posts, and code hosting platforms.
How does Codequiry compare to JPlag and DoloS?
Codequiry offers advantages over JPlag and DoloS including web matching (not just peer comparison), JSON API responses, webhooks for async workflows, more language support, and commercial SLAs. All three are alternatives to MOSS, but Codequiry is purpose-built for API integration.
What's the pricing for code plagiarism detection?
Codequiry plans start at $79/month. All plans include web scanning, JSON results, SDKs, and priority support. Enterprise plans add SSO, dedicated infrastructure, and custom SLAs. Cancel anytime.
Can I integrate with my LMS or CI/CD pipeline?
Absolutely. Codequiry provides a REST API with SDKs for Node.js, Python, PHP, and Java. Webhooks notify your systems when results are ready. Integrate with Canvas, Blackboard, Moodle, GitHub Actions, GitLab CI, Jenkins, or any custom workflow.
How fast is the plagiarism analysis?
Codequiry delivers results in under 2 minutes for most checks, even with 100+ submissions. Our horizontally-scaled infrastructure processes checks in parallel — 50x faster than single-threaded tools like MOSS. Large batch processing and webhooks are available for high-volume workloads.
MOSS alternatives in 2026: which code plagiarism detector wins?
When searching for alternatives to Stanford MOSS, educators and developers typically consider JPlag, DoloS, and Codequiry. Each tool has different strengths for source code plagiarism detection.
JPlag is an open-source tool from KIT that focuses on pair-wise comparison. DoloS uses AST analysis for structural comparison. Both are offline tools without web matching.
Codequiry is the only API-first solution with web-scale matching, JSON responses, and Zeus™ Hyper for advanced anti-obfuscation. It's designed for modern integration workflows.
Quick Comparison
We switched from MOSS to Codequiry's API and immediately started catching plagiarism we'd been missing for years — students copying from GitHub gists, paid solutions, even old Stack Overflow answers. The JSON response let us wire it into our LMS in an afternoon.
The MOSS alternative your team will actually ship with.
Join 5,000+ professors, bootcamps, hiring platforms, and engineering teams using Codequiry's code plagiarism API for source code similarity detection at scale. Get an API key, send your first request, see results in JSON.