Everything you need. Nothing you don't.
A complete practice system — not a pile of features.
A coach, not a spoiler
Three hint levels, problem-aware chat, mistake explanations.
Stuck? Reveal exactly as much help as you want — never more. Tap a level.
Real sandbox
Compiled and executed in isolation — never simulated.
Runtime12 ms
Memory3.1 MB
verdictAccepted
Mock interviews
Live voice or text, scored against a rubric, with a full transcript.
Overallivr.verdict.lean_hire
Communication86
Technical depth78
Problem solving82
Leaderboards
Ranked by real runtime — per language.
🥇 ayse4 ms
🥈 dev_kerem6 ms
🥉 rustacean9 ms
An infinite, shared library
Generate a problem and it's verified in the sandbox, cached in every language, and published for everyone. The library compounds.
Verified before publishSolutions in 13 languagesUpvotes & discussion
An editor you'll love
8 themes, Vim mode, code saved per problem.
13 languages, one standard
Same problem, same tests, byte-identical judging in every language.
PythonJavaScriptTypeScriptJavaC++CGoRustC#KotlinSwiftRubyPHP
Company signals
See which companies actually ask each problem.
AmazonGoogleMetaMicrosoftApple
Ask anything, mid-problem
The mentor sees your code and the problem — so its answers are about your attempt, not generic advice.
Why does my loop miss the last pair?
Stop reading. Start solving.
All of it is one click away — free.
Free forever plan · no credit card