The DMOJ judge-server is the core judging component of the DMOJ (Modern Online Judge) platform, responsible for executing and evaluating programming contest submissions in sandboxed environments. It features a plugin-based architecture supporting over 50 programming languages through language-specific executors, graders, and checkers. The system handles secure sandboxing via ptrace and seccomp (Linux) or ptrace (FreeBSD), manages problem configurations with automatic reloading, and communicates with the judge server using a custom packet protocol. Key entry points include the main judge daemon (dmoj), a CLI tool for local testing (dmoj-cli), and an autoconfiguration utility for runtime detection. The codebase demonstrates strong separation of concerns, with isolated components for sandboxing, subprocess communication, and output normalization that exhibit reusable patterns.
PutongOJ is a full-stack online judge platform built as a pnpm monorepo with TypeScript across the stack. The backend is a Koa 3 server using MongoDB (Mongoose) and Redis, with a separate judger component that executes submissions in a privileged Docker sandbox via go-judge. The frontend is a Vue 3 application using PrimeVue, Pinia, and Vue Router; it provides problem CRUD, testcase management, contest ranklists/status, course management, discussions, and account settings. A shared package (@putong-oj/shared) contains Zod schemas and enums used by both server and client. Although primarily an application, it includes a data migration subsystem and a documented testcase data format, giving it a minor data-engineering flavor.