Built for CS educators

Academic Integrity, Upheld
in Computer Science.

Codequiry checks student code against classmates, the open web, and AI generators in a single upload — so the work that earns the grade is actually theirs. Spend your time teaching, not policing.

Get Started See it in action
student_47.py flagged 92% match
Peer match detected with student_12.py — BFS implementation identical with renamed variables
CS188 Pacman Project • 2 min ago
AI-generated code 78% GPT
Hexagram flagged submission — instructional comments, over-documented, textbook-perfect DP pattern
CS201 HW3 • 5 min ago
Web source found 96% SO
Merge sort implementation copied verbatim from stackoverflow.com/questions/6567941
CS101 Sorting • 8 min ago
Chegg answer detected 87%
BST construction matches homework answer on chegg.com/homework-help — 3 students submitted same code
CS50 Problem Set 5 • 12 min ago
20+
Detection engines
1T+
Sources indexed
65+
Languages
500+
Universities

See exactly what gets caught

Real examples from CS courses. Click the tabs to explore each detection type.

Peer Match 92%
AI Detection 78%
Web Source 96%
Network View cluster
student_a / search.pySource
14def breadthFirstSearch(problem):
15 """Search the shallowest nodes."""
16 frontier = util.Queue()
17 frontier.push((problem.getStartState(),
18 [], 0))
19 explored = set()
20 while not frontier.isEmpty():
21 node, actions, cost = frontier.pop()
22 if problem.isGoalState(node):
23 return actions
24 if node not in explored:
25 explored.add(node)
student_b / search.pyMatch
11def bfs(prob):
12 """BFS search."""
13 q = util.Queue()
14 q.push((prob.getStartState(),
15 [], 0))
16 visited = set()
17 while not q.isEmpty():
18 state, acts, c = q.pop()
19 if prob.isGoalState(state):
20 return acts
21 if state not in visited:
22 visited.add(state)
92% structural matchVariable renamingSame algorithm
CS188 Pacman Project — BFS
submission.pyAI flagged
1# Elegant and efficient DP solution
2def longest_common_subsequence(text1, text2):
3 """Find the LCS using dynamic
4 programming for optimal performance."""
5 m, n = len(text1), len(text2)
6 dp = [[0]*(n+1) for _ in range(m+1)]
7 for i in range(1, m + 1):
8 for j in range(1, n + 1):
9 if text1[i-1] == text2[j-1]:
10 dp[i][j] = dp[i-1][j-1]+1
11 else:
12 dp[i][j] = max(dp[i-1][j],
Hexagram Analysis78% GPT-4
Detection Signals
Instructional commentLine 1
Over-documented docstringLines 3-4
Uniform variable namingLines 5-6
Textbook-perfect structureLines 9-12
Verdict: AI-generated
ChatGPT 78% • Claude 12% • Gemini 4%
78% ChatGPT12% ClaudeHexagram v2
CS201 — Dynamic Programming
student_submission.jsWeb match
1function mergeSort(arr) {
2 if (arr.length <= 1) return arr;
3 const mid = Math.floor(arr.length / 2);
4 const left = arr.slice(0, mid);
5 const right = arr.slice(mid);
6 return merge(mergeSort(left),
7 mergeSort(right));
8}
9
10function merge(left, right) {
11 let result = [], i = 0, j = 0;
12 while (i<left.length && j<right.length){
Matched Sources4 found
stackoverflow.com
/questions/6567941/merge-sort-js
96%
Lines 1-7
github.com
trekhleb/javascript-algorithms
44%
Lines 10-12
chegg.com
/homework-help/sorting-impl
31%
Lines 1-5
coursehero.com
/file/cs101-sorting-assignment
87%
Lines 1-7
96% StackOverflow44% GitHub87% CourseHero
CS101 — Sorting Algorithms
A B C D E F G 92% 41% 87%
Cluster detected: Students A, B, D
3 submissions share 87-92% structural similarity. Likely collusion ring.
High risk Medium Low Clean
Collusion cluster3 students flagged4 clean
CS188 — 47 submissions analyzed

The most comprehensive code plagiarism checker — 20+ engines per check

MOSS is one of many. Every submission is analyzed by all engines simultaneously — peer-to-peer, AI detection, and web search run together.

M

MOSS

Stanford's Measure of Software Similarity. Rebuilt with winnowing fingerprinting and multi-threaded processing on dedicated infrastructure.

Unlimited checks25+ languages
H

Hexagram

Proprietary AI detection engine. Identifies code written by ChatGPT, Claude, Gemini, and Copilot through pattern analysis of commenting style, structure, and naming.

v2.0.1AI models
Z

Zeus

Structural code comparison engine. Compares every submission against every other in the class. Catches variable renaming, reordering, and obfuscation attempts.

Peer-to-peerCluster detection
W

Web Search

Scans 1T+ indexed sources including StackOverflow, GitHub, Chegg, CourseHero, Brainly, GitLab, Bitbucket, and academic repositories.

1T+ sourcesReal-time
D

Dolos

Token-based analysis engine. Fast, language-agnostic comparison that catches structural similarities even when surface-level code looks different.

65+ languagesFast
J

JPlag

Graph-based comparison with token sequence matching. Industry-standard engine used by universities worldwide alongside Codequiry's own engines.

Graph analysisEstablished

Built for how professors actually work

Not just detection — a complete workflow from upload to academic hearing.

Side-by-side comparison

Line-by-line highlighted matches

Every match shows the exact lines, highlighted and aligned. Click any match to see the source — whether it's another student, a web page, or an AI pattern.

student_a.py
pivot = arr[mid]
left = [i for i in arr
if i < pivot]
student_b.py
p = lst[middle]
lo = [x for x in lst
if x < p]
Risk scoring

Estimated unoriginality

Every submission gets a composite risk score combining peer match, web match, and AI detection into one number.

84
HIGH RISK
Peer 92%Web 64%AI 78%
Integrations

LMS + API + CLI

Connect Canvas, Moodle, or Blackboard via LTI. Or use the REST API with SDKs for Node.js, Python, Java, Go, and PHP.

Canvas Moodle Blackboard REST API CLI
Reports

PDF reports for academic hearings

Generate detailed, printable PDF reports with all evidence — matched lines, source URLs, AI confidence scores, and similarity percentages. Ready for academic integrity committees.

PDF Export CSV Export Print
Team

50,000 seats

Admin, TA, and instructor roles. Bulk import students, share results across your department.

Storage

100GB included

File manager with folders, starring, trash, and recovery. All results stored permanently.

Compliance

FERPA + GDPR

SOC 2 Type II certified. Full audit logs, data disclosure tracking, and student privacy controls.

Stanford MOSS vs Codequiry's source code plagiarism checker

Same algorithm at its core. Everything else is better.

CapabilityStanford MOSSCodequiry
SubmissionsRate limitedUnlimited
AI detectionNoneChatGPT, Claude, Gemini
Web searchNone1T+ sources
ProcessingSingle-threadedMulti-threaded, dedicated
Cluster detectionNoneNetwork graph analysis
InterfacePerl scriptWeb, API, CLI, Desktop, LMS
Results14 daysPermanent + PDF export
Languages~2565+
LicenseAcademic onlyCommercial

Code plagiarism checker — frequently asked questions

Everything educators ask before switching from MOSS.

What is a code plagiarism checker?

A code plagiarism checker is software that detects similarities between source code submissions. Unlike text plagiarism tools, it analyzes program structure, tokens, and logic rather than literal text — so it catches copied code even when variables are renamed, comments are stripped, or whitespace is reformatted. Codequiry runs 20+ detection engines (including Stanford's MOSS, JPlag, Dolos, and Zeus) on every check.

What is the best code plagiarism checker for educators?

Codequiry is purpose-built for CS educators. It combines Stanford's MOSS algorithm with AI-generated code detection, web source matching, and peer-to-peer comparison in a single upload. It supports 65+ languages, integrates with Canvas, Moodle, and Blackboard, and produces FERPA-compliant PDF reports suitable for academic integrity hearings.

Can Codequiry detect AI-generated code from ChatGPT, Claude, or Copilot?

Yes. Codequiry's proprietary Hexagram engine identifies code written by ChatGPT, Claude, Gemini, and GitHub Copilot through pattern analysis of commenting style, structural choices, and naming conventions. AI detection runs automatically alongside traditional plagiarism checks on every submission.

What programming languages does the code plagiarism checker support?

Codequiry supports 65+ programming languages including Python, Java, C, C++, C#, JavaScript, TypeScript, Go, Rust, Ruby, PHP, Swift, Kotlin, Scala, R, MATLAB, SQL, HTML/CSS, Haskell, Lisp, and many more. All languages run through the same 20+ engine pipeline.

Is Codequiry a MOSS alternative?

Codequiry is a complete MOSS alternative. It includes MOSS as one of its 20+ engines but adds AI detection, web search across 1 trillion sources, faster processing on dedicated infrastructure, unlimited checks, modern UI, LMS integration, an API, and CLI access. MOSS users typically migrate to remove the queue waits, file-size caps, and lack of AI detection.

How does the code plagiarism checker handle variable renaming and obfuscation?

The Zeus engine performs structural comparison at the AST and token level, which makes it immune to variable renaming, statement reordering, comment stripping, and whitespace changes. JPlag and Dolos add additional token-sequence and graph-based detection layers, so students cannot trivially defeat the checker by refactoring identifiers.

Is there a free option to check code?

Educators and researchers can request access to the free MOSS server for unlimited Stanford MOSS hosting. For the full 20+ engine pipeline (AI detection, web search across 1T+ sources, unlimited deep checks, side-by-side reports, LMS integration), plans start at $499/month with the Grow tier.

Can the code plagiarism checker integrate with Canvas, Moodle, or Blackboard?

Yes. Codequiry provides direct LMS integration with Canvas, Moodle, and Blackboard, plus a REST API and CLI for custom workflows. Submissions can be pulled automatically from assignments, checked, and the results posted back to the gradebook without leaving your LMS.

Stop chasing MOSS limitations.
Start catching everything.

Included with the Advanced plan. Cancel anytime.

Get Started Advanced plan • $1999/mo • MOSS + AI + Web + 20 engines

Explore Codequiry's code plagiarism detection toolkit

Dig deeper into the most accurate source code plagiarism checker on the market — covering every language, every detection engine, and every academic-integrity use case.

→ Code Plagiarism Checker → Plagiarism Checker for Code → What Is Code Plagiarism? → Code Plagiarism Detection Software → How to Detect Code Plagiarism → Code Plagiarism vs MOSS → Codequiry vs Dolos vs MOSS → Free Code Plagiarism Checker → Code Plagiarism Checker for Teachers → AI Code Detector → Detect AI-Written Code → Quick Code Plagiarism Check → Free MOSS-Compatible Server