DMOJ
What it is
DMOJ is an open-source platform for programming contests and an archive of competitive programming problems. Its archive includes tasks from past CCC, CCO, COCI, IOI, and JOI competitions, along with other sources, and the site runs the DMOJ Monthly Open Programming Competition. Organizers can use formats such as ICPC, IOI, AtCoder, and ECOO, with system testing, hidden scoreboards, and virtual participation. Judging features include interactive tasks, custom output validators, per-language resource limits, and support for scaling to hundreds of judging servers. Problem statements can include Markdown, LaTeX, figures, syntax highlighting, downloadable PDFs, and editorials. The contest system integrates with Stanford MOSS for plagiarism checks. DMOJ supports OAuth login, two-factor authentication, and staff permissions. Public contest hosting is free; educational organizations can ask about private contests for a small fee, with no amount listed. Self-hosting documentation is available, and the installation guide says the site is tested with MySQL and is unlikely to work with other databases. AI use is prohibited in rated contests and judging resources cannot be used for AI training.
For and against
For
- Free public contest hosting at no cost
- Supports multiple contest formats and virtual participation
- Includes problem archive and programming autograding
- Self-hosting documentation is available
Against
- Private contest hosting has an unstated small fee
- Self-hosting is unlikely to work with databases besides MySQL
- AI use is prohibited in rated contests
The verdict
DMOJ brings a programming problem archive, contest tools, and judge capabilities together in an open-source platform. Review the MySQL caveat and AI-use restrictions before choosing it for self-hosting or rated contests.
Who it suits
DMOJ suits competitive programmers, contest organizers, and educational organizations looking for programming autograding or contest hosting. It also fits teams that want to self-host and can use MySQL.
Plans and prices
Public contest hosting
Public contests hosted on DMOJ
Read 4 Oct 2026 · dmoj.ca
Private contest hosting
For educational organizations; small fee, amount not stated
Read 4 Oct 2026 · dmoj.ca
On the record
- Audience
- DMOJ offers free public contest hosting and says educational organizations can contact it about hosting private contests for a small fee.dmoj.ca · read 4 Oct 2026
- Authentication and access
- The platform supports OAuth login with Google, Facebook, and GitHub, two-factor authentication, and fine-grained staff permissions.github.com · read 4 Oct 2026
- Contest formats
- The contest system supports ICPC, IOI, AtCoder, and ECOO formats, along with system testing, hidden scoreboards, and virtual participation.github.com · read 4 Oct 2026
- Contests
- DMOJ runs the DMOJ Monthly Open Programming Competition for people interested in competitive programming.dmoj.ca · read 4 Oct 2026
- Judging
- The platform supports interactive and signature-graded tasks, runtime data generators, custom output validators, per-language resource limits, and scaling to hundreds of judging servers.github.com · read 4 Oct 2026
- Plagiarism integration
- The contest system integrates with Stanford MOSS for plagiarism checking.github.com · read 4 Oct 2026
- Problem archive
- The site hosts problems from past CCC, CCO, COCI, IOI, and JOI competitions, as well as other sources.dmoj.ca · read 4 Oct 2026
- Problem statements
- Problem statements support Markdown, LaTeX math and figures, syntax highlighting, PDF generation, and built-in editorials.github.com · read 4 Oct 2026
- Purpose
- DMOJ is a modern contest platform and archive of programming problems, and is entirely open source.dmoj.ca · read 4 Oct 2026
- Security reporting
- DMOJ asks researchers to send potential security issues privately for responsible disclosure before making them public.dmoj.ca · read 4 Oct 2026
- Self-hosting
- The maker provides documentation for installing the DMOJ site and judge.github.com · read 4 Oct 2026
- Self-hosting requirement
- The installation guide says the site is tested to work with MySQL and is unlikely to work with other databases.github.com · read 4 Oct 2026
- Support
- The site asks users with questions about hosting contests to contact a moderator.dmoj.ca · read 4 Oct 2026
- Use restrictions
- DMOJ says AI use is prohibited in rated contests and use of its judging resources for AI training is prohibited.dmoj.ca · read 4 Oct 2026
