CodeKairo Battles · coding tournaments

Host a coding tournament. Let the judge run it.

1v1 knockouts and ICPC-style team contests for colleges, clubs and companies, on a catalogue of about 600 problems judged by hidden tests in 13 languages. Free to host. Players enter with their CodeKairo account, and every solve counts on their profile.

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Free to host. One CodeKairo account for players and organizers.

A knockout, start to finish

Mon
The coding club publishes a knockout for @college.edu addresses.
09:00
Check-in opens. 29 players confirm and are seeded by rating.
10:00
Round of 32: one problem, 45 minutes, first Accepted wins.
13:50
The final is settled. The champion's result is on their profile.

An example day. The organizer sets the dates, the match length and who may enter.

What is CodeKairo Battles?

CodeKairo Battles is a free tournament platform on which colleges, clubs and companies host coding competitions — 1v1 knockouts and ICPC-style team contests — judged live on CodeKairo's problem catalogue in 13 programming languages. An organizer creates an organization, has it verified by CodeKairo, and drafts a tournament: the format, the dates, who may enter — anyone, listed email domains, an invite code, the organizer's approval, or a mix — and up to 15 problems from a catalogue of about 600, each judged by hidden tests. In a knockout, players register themselves, check in during the hour before the start and are seeded by rating into a bracket where every match is one problem against the clock. In an ICPC-style contest the organizer enters teams of up to three, and the scoreboard ranks by problems solved and penalty time, with an optional freeze before the end. Players use the account they already have on CodeKairo, and every accepted solve counts on their CodeKairo profile. Hosting is free.

Who is it for?

Organizers: coding clubs, student chapters, college departments and placement cells, and companies running a campus or community contest — anyone who wants a judged event without building or renting a judge. Players: students and developers who want to compete for their college or club on the account, the editor and the 13 languages they already practise in.

Two formats

  • 1v1 knockout — Players register, check in and are seeded by rating into a bracket. Every match is one problem on a clock, won by the first accepted solution or, at time, by the most hidden tests passed.
  • ICPC-style contest — Teams of up to three against one problem set on one clock, ranked by problems solved and then penalty time, with a scoreboard that can freeze before the end.

Open and upcoming

No tournament is open right now.

Recently finished

Organizers

How hosting works

  1. Create your organization. The official name, the kind, the website and a line about it. Draft tournaments straight away; CodeKairo verifies the organization before its first tournament goes public, and again if its details change.
  2. Draft the tournament. Pick the format, the start, the match or contest length and when registration closes. Choose up to 15 problems from the catalogue; players see only how many until the start.
  3. Decide who may enter. Anyone; addresses on your email domains; holders of an invite code; people you approve — or a mix, with an optional cap. For a contest, paste the team list instead.
  4. Publish, share, and let it run. Share the tournament's page. Every entrant is emailed a day and an hour before the start, and you can send another reminder whenever you like. On the day, check-in, the bracket, every match, the scoreboard and the results run without you; you approve registrations, watch matches and reveal a frozen board.

Hosting a tournament, in full

How playing works

  1. Find your tournament. The tournaments page lists what is open for registration and what is live, from verified colleges, clubs and companies. Your organizer may also send you the link.
  2. Register, or be entered. Register yourself for a knockout; for a contest the organizer enters your team. Your own registrations and their status sit at the top of the tournaments page.
  3. Turn up and solve. Check in for a knockout in the hour before the start. The match or contest room is the CodeKairo editor you know, with the problem, the clock and — in a knockout — your opponent's progress.
  4. Keep what you earned. Solves count on your CodeKairo profile, the problem carries a solved-in-a-tournament mark, and your placement sits in your profile's Tournaments section.

Taking part, in full

Which languages does the judge accept?

JavaScript, TypeScript, Python, Java, C++, C, C#, Go, Kotlin, Swift, Rust, PHP, Ruby.

Frequently asked questions

How much does it cost to host a tournament?
Nothing. Hosting on CodeKairo Battles is free: the organization, drafting and publishing tournaments, the judge, the bracket, the scoreboard and the results. Players need only a free CodeKairo account.
Who can host a tournament?
Anyone signed in can create an organization — a college or university, a student club or chapter, a company or a community — and draft tournaments straight away. A tournament becomes public only once CodeKairo has verified its organization — before its first public event, and again if the organization's details change; the official name and website make that quick.
Can I edit or delete a tournament after creating it?
Yes, until it starts. A draft can be changed freely. Changes to a published tournament go to CodeKairo for approval, and it is hidden from players until they are approved; every registration is kept. A tournament that has not started can be deleted, with its registrations; once it has started it can only be cancelled, because its results are on players' profiles. Editing a verified organization sends it back for verification, and its tournaments are hidden until then.
Do I need a separate account for Battles?
No. Battles uses your CodeKairo account: sign in on Battles with email, Google or GitHub, or arrive already signed in from codekairo.com. An account created on Battles works on CodeKairo too, and both are free.
Do tournament solves count on my CodeKairo profile?
Yes. An accepted submission in a tournament is an ordinary CodeKairo submission: it counts toward your solved problems, activity heatmap, streak and roadmap stages, and pays XP the first time you solve that problem. The problem is marked as solved in a tournament, and your profile lists every tournament you played with where you finished.
Which languages can I use?
All 13 the CodeKairo judge accepts: JavaScript, TypeScript, Python, Java, C++, C, C#, Go, Kotlin, Swift, Rust, PHP, Ruby.