# hydro-dev/Hydro

Hydro - Next generation high performance online-judge platform - 新一代高效强大的信息学在线测评系统 (a.k.a. vj5)

Repository: https://github.com/hydro-dev/Hydro
Canonical: https://ross.abutalabs.com/products/hydro
Homepage: https://hydro.js.org/
Language: TypeScript
License: AGPL-3.0
License Family: copyleft
Topics: onlinejudge, hydro, oj, noip, mongodb, mixed-judge, node, oi, online-judge, acm-icpc, vijos, vj5, cpp, java, python
Last push: 2026-08-25T14:29:19+00:00

## Health v2 (maintenance only)
Score: 67/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 8, longevity 100
- inputs: {"age_days": 2345, "days_push": 8, "days_rel": 507, "gap_med": null, "n_releases_24m": 1}
- flags: prerelease_only
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 6891, forks 470 (observed 2026-08-28T04:09:51.144893+00:00)

## What it is
Hydro is a high-performance, self-hostable online judge platform for competitive programming and informatics education, built in TypeScript on Node.js with MongoDB. It features a modular plugin system, multi-domain workspaces, fine-grained permissions, support for many contest formats and problem types, and built-in VJudge-style problem importing from other OJ platforms.

## Use cases
- host a competitive programming online judge for a school or university
- run ACM/ICPC, OI, or IOI style contests with automatic code judging
- set up homework and practice problem sets for programming classes
- import problems from Codeforces, Luogu, or HUSTOJ into a private judge
- self-host a scalable judge that runs on a Raspberry Pi or ARM server
- manage multiple classes or institutions in one judge instance with isolated domains

## When to choose
- you need a full-featured, actively maintained online judge with contest, homework, and rich problem-type support
- you want horizontal scalability with stateless nodes and auto-balanced judging queues
- you need extensible functionality via a plugin system and smooth upgrades
- you want one-click install on Linux including ARM devices

## When to avoid
- you only need a tiny single-user code runner or sandbox without a web platform
- your infrastructure is Windows-only, since Hydro targets Linux
- you require a judge in a language other than the supported C++/Java/Python set without extra setup
- you cannot run MongoDB or prefer a fully managed SaaS without self-hosting

## Facets
- artifact type: application
- maturity: active
- function: web-framework, plugin-system, api-framework
- domain: education, developer-tools, web-development, self-hosted
- platform: self-hosted
- tags: online-judge, competitive-programming, code-evaluation, acm-icpc, oi, mongodb, typescript, contest-management, vjudge, problem-bank, sandbox, linux, nodejs, docker, web-server

## Member repositories
- hydro-dev/Hydro (main) score 67

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:51.144893+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:41:38.876317+00:00, confidence not recorded.
  - readme: https://github.com/hydro-dev/Hydro (fetched 2026-08-28T04:09:51.144893+00:00, sha c9314fc6dc9e)
  - homepage: https://hydro.js.org/ (fetched 2026-08-29T08:37:42.457985+00:00, sha 44136fa355b3)
- Data as of 2026-08-30T08:39:29.467469+00:00.