AtCoder (competitive programming)
Japan's top competitive-programming judge, in English — clean problems and a rating you can climb.
- Computer Science
- Who can enter
- Anyone worldwide — free; contests have full English support
- What it costs
- Free to compete in the contests. There is an optional paid membership for extra practice material, but the rated contests are free.
- When it closes
- We could not confirm this year's date against the organiser's own page, so we are not showing a countdown for it. Last published: Rated contests most weekends — no registration deadline.
Sending this to someone sends the four facts above, not just a name — they will see who can enter and what it costs before they decide.