AtCoder
AtCoder: A free, contest-focused platform with deep archives, ratings, editorials, and broad language support. Ranked #5 of 30 in Coding Challenge Platforms by our editors (8.8/10); pricing: Free plan; best for algorithm and optimization contests.
At a glance
- Editor score8.8 / 10
- PricingFree plan
- Best forAlgorithm and optimization contests
- Free planYes
- Paid fromFree
- Primary useContests
- Founded2012 · Tokyo, Japan
- Facts checked22 Sep 2026
Where it wins
- Free timed algorithm and heuristic contests
- More than 5,000 archived problems with official editorials
- Supports many programming languages and rating systems
Where it doesn't
- Primarily focused on contests rather than broader coding workflows
- Web-only access limits platform flexibility
- Recruitment and assessment services are separate products
Our verdict on AtCoder
AtCoder is a browser-based competitive programming platform for people who want structured algorithm and optimization contests. Operated by AtCoder Inc., it hosts beginner, regular, grand and heuristic formats, with timed submissions judged online. Participants receive algorithm and heuristic ratings, can review completed contests, and can work through a large archive of past problems. Practice contests for first-time users make the platform suitable for learners, while the contest formats and rating systems also serve experienced competitors.
The core platform is free, which keeps the entry barrier low for individual practice and recurring participation. Its main value comes from the combination of live contest formats and a library of more than 5,000 archived problems. Official editorials add a useful learning layer after contests, helping users study intended approaches rather than relying only on accepted submissions. Language coverage is unusually broad, including C, C++, C#, Java, Python, Rust, Ruby, Go, Kotlin, Swift, JavaScript, TypeScript, PHP, Scala, Haskell, SQL and many others. That breadth supports participants who prefer different programming ecosystems.
AtCoder’s strongest fit is for users who specifically want competitive programming, measurable ratings and algorithmic or heuristic problem solving. Its browser-based code execution and online judging keep the workflow centered on submitting solutions under contest rules. The trade-off is focus: it is not presented as a general-purpose coding workspace, and the core website is primarily about contests and practice. AtCoder Inc. also operates TOPSIC for programming assessments and AtCoderJobs for recruitment, but those are separate services rather than paid tiers of the core product. Choose AtCoder for contest-led development and optimization practice; consider a broader coding platform if project work or integrated recruitment workflows are the priority.
Your product? Our editors can test AtCoder in depth and publish a review, labelled as paid · from $149/mo →
AtCoder pricing
AtCoder fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| Primary use | Contests |
| Languages supported | C, C++, C#, Java, Python, Rust, Ruby, Go, Kotlin, Swift, JavaScript, TypeScript, PHP, Perl, Lua, Scala, Haskell, OCaml, Nim, Pascal, R, SQL, Prolog, PowerShell, Bash, Fortran, COBOL, Julia, Dart, Elixir, Erlang, F#, D, Crystal, Clojure, Common Lisp, Scheme, Visual Basic, Lean, LLVM IR, Octave, SageMath, Mercury, Pony, Brainfuck, APL, AWK, BASIC, Assembly, Befunge93, Piet |
| Problem library size | 5000 problems |
| Solution explanations | Yes |
| Custom challenges | Not verified |
| Company assessments | Not verified |
| Deployment | Cloud |
| Platforms | Web |
| Support | Tickets, Docs |
| Built for | Solo, Small business, Mid-market, Enterprise (editorial estimate) |
| Pricing | Free plan |
| Website | atcoder.jp |
| Facts checked | 22 Sep 2026 |
Alternatives to AtCoder
- LeetCodeA broad coding practice platform with judging, contests, study plans, and interview tools.9.4
- ExercismA free exercise platform combining broad language coverage, automation, and human feedback.9.2
- CodewarsA free, language-rich kata platform for structured practice and community learning.9.0
See all AtCoder alternatives →
AtCoder vs the competition
- AtCoder vs LeetCode
- AtCoder vs Exercism
- AtCoder vs Codewars
- AtCoder vs Codeforces
- AtCoder vs GeeksforGeeks Practice
- AtCoder vs Frontend Mentor
Compare AtCoder with any tool side by side →
Used AtCoder? Be the first to review it
The editor score above is our own research. What this page doesn't have yet is a reader's view — what you used AtCoder for, what worked and what didn't. No stars are seeded and no review is paid for; an editor reads every one before it appears.
Write a reviewTwo minutes · verified accounts only · read by an editor before it appears
Featured on iTechGuides
AtCoder is listed in our Coding Challenge Platforms directory. Add the badge to your site — it links back to this page.
<a href="https://www.itechguides.com/products/atcoder/"><img src="https://www.itechguides.com/best/badge/atcoder.svg" alt="Featured on iTechGuides" width="230" height="46"></a>
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.
Last updated · How we research and update