TL;DR: I couldn't register on usaco.org (Gmail verification bug), so I built OJCloud — all 484 USACO problems (2011–2024, Bronze → Platinum) on a modern judge with partial scoring, 16 languages, real-time per-test-case verdicts, progress tracking, and both ICPC/IOI contest modes. Everything uses standard I/O. Register with just a handle + password — no email, no OAuth, no waiting. Hello, Codeforces!
I've been using USACO problems to train for years, but practicing them on usaco.org always felt unnecessarily painful — so I built a judge that just works.
Please join our Discord so you can feedback anything about our website (I know it has some troubles and I need your help !)
The friction is real: Gmail users often don't receive verification emails and the only fix is emailing the contest director personally. Pre-2020 problems silently require file I/O — your code compiles, runs, produces correct output locally, but gets WA on the judge with zero explanation (this is the #1 cause of "it works on my machine" reports). There's no dashboard to track what you've solved, and the submit button is buried at the bottom of a static archive page.
I put all 484 USACO problems (2011–2024, Bronze through Platinum) on OJCloud with a proper judge. Everything uses standard I/O — no file I/O surprises.
What you get
- Partial scoring — no more guessing whether you failed 1 test case or all 20. You see exactly how many tests pass out of the total.
- 16 languages — C++20/17/14/11, Python 3, PyPy 3, Java 21/8, Kotlin, Go, Rust, and more
- Real-time judging — live verdict per test case as the judge runs, not a spinner followed by a wall of results
- Progress tracking — solved count, acceptance rate, activity heatmap, submission history. You know where you stand.
- Polygon-compatible checkers — 10 built-in testlib.h checkers (wcmp, lcmp, fcmp, ncmp, rcmp, hcmp, yesno, ...) + custom checker support
- Contest system — both ICPC and IOI scoring formats, live standings
- Bilingual — full English + Vietnamese interface, auto-detected from your location
Try it
484 problems and 5,000+ test cases are live. Register with just a handle and password at app.ojcloud.net — no email required. Pick a USACO problem, submit, and see the judge in action.
Thanks to MikeMirzayanov for Codeforces and testlib.h — many of our design decisions were inspired by Polygon.
Another reason is i've just learned about devops and wanna try to serve some users, thank you for your attention !
Could you add a function to hide the "tags" ?
Can you DM me via discord, it would be easier for me to develop new feature.
Dm'ed you as well and pinged in your server !
Auto comment: topic has been updated by ZhangShan (previous revision, new revision, compare).
Can u tell whats the approximate rating equivalent like i dont want to do very hard problems. Thanks.
wdym :v
Thanx a lot lot lot
Hi, just tried this, my code that works on usaco.org does not work here: https://app.ojcloud.net/submissions/292
Edit: nevermind, this was because I was using USACO's file/IO instead of stdin/stdout; it actually does work
Why did Brian Dean request that the USACO problems be removed from the WCIPEG online judge? just so you know..
I think i would try to contact usaco team about this in the future after i done some kind of work, i just think it's a great idea because of the friction of creating an account in usaco.org and many sites have usaco.org problem and test too, but for sure, thank you for your information, the information is really helpful for me.
nice project dude
thank you bro
It wouldn't let me register as well, and it was bugging me a lot. Thanks a lot, I'll use it.
very nice to see u happy !
Nice UI, It also gives estimated CF rating which helps to not do harder problems as a beginner to a new topic, Only thing is the tags are right below the problem, I think u should add an option to disable tags so they hide. But keep the sort by tag function while the tags are hidden (incase there are multiple tags this helps in not knowing the other concepts involved in the problem kinda niche thing to ask but just a recommendation).
can you contact me via my discord so i could have feedback from you, very thank you !!!
you can't register if you add a space in either your first name or last name, that can be helpful to fix it sometimes
can you join our discord and tell me exactly what's the problem, thank you for your attention on our website !
Auto comment: topic has been updated by ZhangShan (previous revision, new revision, compare).
orz
This is great!
The platform is great, but there is a critical issue regarding the judge.
In this submission, the source code is a no-op and should result in a WA. However, the judge incorrectly reports a RE. Since the integrity of the judge is the most vital part of any OJ, please prioritize fixing this bug.
Note: I have ruled out File I/O issues, as my non-File-I/O solution passed the tests.
Thank you for using my site !, if any problem occur, please contact me via my discord for the fastest fix, i know it has troubles !
Auto comment: topic has been updated by ZhangShan (previous revision, new revision, compare).
I have a recomandation that is while solved problem the other solution must visible to us for studying others solution . Anyways,thanks for this . ORZ!
wdym other solution, can you contact me via discord to talk about this further ?