Dolos
Ghent University source code plagiarism detector, free in the browser and MIT-licensed
Key data
| Company | Ghent University (Team Dodona) |
|---|---|
| Category | Plagiarism Checkers |
| Headquarters | Ghent, Belgium |
| Founded | Not stated |
| EU Presence | Yes - Belgium (EU) |
| Data Location | Not stated; self-hosting and CLI keep files on your own machine |
| Open Source | MIT |
| GDPR Compliant | Yes |
| Self-Hosting | Yes - self-host guide, CLI and Docker image documented |
| Main Features | Source code similarity detection, web app, CLI and library, API, Docker, Tree-sitter parsers, analytics dashboards, clusters of suspect cases |
| Pricing | Free web application; open source under the MIT licence |
| Best For | Programming teachers who need to compare student code submissions, not written essays |
| Replaces | Turnitin |
Full review
Dolos is developed by Team Dodona at Ghent University in Belgium, and the project cites its research in SoftwareX (2024). The project page describes Dolos as a free web application with no installation, secure, private and fast.
Dolos handles source code, not prose. It tokenises code with Tree-sitter, so renaming variables or functions does not hide a copy.
How Dolos detects code plagiarism
Dolos works in four steps: tokenization, fingerprinting, indexing and reporting. Tokenization masks variable and function names so that renamed copies still match.
The report shows analytics dashboards with hierarchical navigation. Clusters of suspect cases let a teacher zoom in on groups of similar submissions.
Running Dolos yourself
Dolos ships as a web app, a CLI, a library and a Docker image, and the documentation includes a self-hosting guide. Dolos is licensed under the MIT licence.
Out of the box Dolos supports Bash, C, C++, C#, Elm, JavaScript, Java, PHP, Python and TypeScript. Further languages can be requested or added locally.
Dolos compared with Turnitin
Dolos covers a use case Turnitin's pages we read do not list: comparing code submissions inside a class. Dolos does not check essays against the web or journals.
Dolos costs nothing, but the project gives no service-level terms or support contract on the pages we read.
Points against
Dolos only analyses source code, so it cannot replace a text similarity service for essays or theses. The pages we read name no support contract or hosting terms for the web app. The legal entity is the university, with no company imprint. For written work use PlagAware or Compilatio.
Is Dolos right for you?
Computer science teachers and teaching assistants who compare student programming assignments and want a free, inspectable tool.
What works, what does not
Pros
- Free web application
- MIT-licensed and self-hostable
- Tree-sitter parsers cover many languages
- Cluster dashboards for suspect cases
- Published research behind the method
Cons
- Source code only, not prose
- No support contract on the pages we read
- Hosting of the web app not stated
- Default language list is limited to common languages
Pros and Cons
Pros
- Free web application
- MIT-licensed and self-hostable
- Tree-sitter parsers cover many languages
- Cluster dashboards for suspect cases
- Published research behind the method
Cons
- Source code only, not prose
- No support contract on the pages we read
- Hosting of the web app not stated
- Default language list is limited to common languages
Alternatives to Dolos
More European plagiarism checkers you can weigh against it:
See all European plagiarism checkers or compare them directly against Turnitin on our alternatives page.
Questions buyers ask
For source code, yes. Dolos is developed at Ghent University in Belgium, is free and open source, and compares code submissions. It does not check essays.
Yes. The Dolos documentation has a self-host guide, and the CLI can run through Docker.
Dolos is licensed under the MIT licence, according to the project page.