Source code plagiarism checker for 65+ languages
Codequiry reads source code as code, in more than 65 programming languages. It compares the structure of each program, so renamed variables, new comments, reformatting and even translation into another language do not hide a copy.
Checks every file against classmates, the web and AI, in 65+ languages.
two_sum.pytwoSum.jsTranslation changes every token but not the algorithm: the same lookup, the same check, the same order. Comparing structure is what lets the two line up.
Used in programming courses at
What a real report looks like
This is one C file from a real check. All 59 lines sit inside a match, and every source is listed by score, from GitHub and Stack Overflow to Chegg. Compare opens any of them side by side with the submission, so you can see the evidence for yourself.
GitHub usernames are removed from the list above. The report shows where the overlap comes from, and a person reviews it and makes the call.
65+ languages
Pick the language when you create an assignment, or let it be detected, so keywords, operators and literals are read the way that language defines them.
General purpose
- Python
- Java
- C
- C++
- C#
- JavaScript
- TypeScript
- Go
- Rust
- Kotlin
- Swift
- Ruby
- PHP
- Scala
- Dart
- Objective-C
Data and science
- Jupyter notebooks
- R
- MATLAB
- Julia
- SQL
- Fortran
Functional
- Haskell
- F#
- Elixir
- Erlang
- Scheme
- Lisp
Systems and hardware
- Assembly
- Verilog
- VHDL
- SPICE
- Ada
- COBOL
- Pascal
Scripting and web
- Shell
- Perl
- Lua
- Groovy
- Tcl
- HTML
- CoffeeScript
Plus plain text, Markdown, YAML and more for the files that come with a project.
How it reads code
- Structure, not text. Names, comments and whitespace drop out before anything is compared, so a renamed copy matches almost as strongly as an exact one.
- Across languages. A solution translated from one language to another keeps its structure, as in the example above.
- Whole projects. A submission can be one file or a ZIP of folders, including mixed languages and Jupyter notebooks.
- Starter code left out. Upload the code you handed out and matches against it are removed.
For the methods behind this, from winnowing fingerprints to syntax trees, see code similarity detection methods compared.
What it checks against
Other submissions
Every file against every other in the assignment, and against earlier terms.
The web
GitHub, Gists, Stack Overflow, Software Heritage and the indexed web.
AI-written code
ChatGPT, Claude, Gemini and Copilot output, with the reasons shown.
Evidence
Every match opens side by side with the shared lines marked.
Coming from MOSS? It compares about 25 languages and only within the batch. Here is the difference.
Check code in any language
Upload a batch and see matches against each other, the web and AI.
Frequently asked questions
What is a source code plagiarism checker?
A tool that compares program source code, not prose, to find work copied from other students, the web or AI. It reads the structure of the code, so renaming, reformatting and new comments do not hide a copy.
Which programming languages are supported?
More than 65, including Python, Java, C, C++, C#, JavaScript, TypeScript, Go, Rust, Kotlin, Swift, R, MATLAB, SQL, assembly, Verilog and Jupyter notebooks. The language can also be detected automatically.
Can it detect code translated into another language?
Often, yes. A solution rewritten from Python into Java or JavaScript keeps the same structure, and structure is what gets compared.
Can it check projects with many files or mixed languages?
Yes. Each submission is uploaded as one ZIP with as many files and folders as it needs, and every file in it is checked.
Does it check code against GitHub and Stack Overflow?
Yes. Every file can be checked against GitHub, Gists, Stack Overflow, Software Heritage and the indexed web, alongside the other submissions and an AI check.
Is there a free source code plagiarism checker?
Yes. The free check compares up to 20 submissions with each other, with no account. Web and AI checks come with a paid plan or a single check.
Check source code in 65+ languages
Every file compared by structure against other submissions, the web and AI.
Get Started Just one assignment? Run a deep scan