Aizu Online Judge
Work through graded programming courses and thousands of judge problems from Japan
Aizu Online Judge (AOJ) is a free online judge developed and run by the University of Aizu in Japan. You submit solutions and the judge grades them automatically, with statistics on how many users solved each problem.
Free · Browser · Intermediate
About Aizu Online Judge
Alongside an archive of more than 3,000 problems, AOJ has structured courses: Introduction to Programming I and II, Algorithms and Data Structures I, and library-style topics such as data sets and queries or discrete optimisation. That makes it useful both for beginners learning their first algorithms and for contest practice.
The interface and messages are available in English and Japanese. It runs in the browser and is free. There is also an API used by third-party command-line submitters.
On Breakpoint since 31 Oct 2026.
Made this game? Claim it →
Tips and discussion
No tips yet.
Sign in to share a tip.