Kattis
Kattis is a free online programming service that accepts code through a browser editor, file uploads or a submission client.
What Kattis is
Kattis is a free online programming service that accepts code through a browser editor, file uploads or a submission client. It compiles or syntax-checks submissions, runs them against test cases and reports results such as wrong answer, time limit exceeded or runtime error. Users can submit repeatedly while working toward acceptance; sample data and personal data can be used for checks, but Kattis must receive a submission to decide acceptance. The service is described for education and recruiting, including applicant screening with coding challenges and programming competitions. It includes a question bank and programming autograding, but not math autograding, written-work OCR or LMS/LTI support. The Python submission client requires Python 3, requests and lxml, and is provided without a guarantee for a particular system. Personal accounts may not be shared, and each person may have one. Linux and web are listed platforms.
Good
- Free plan with Linux and web access
- Browser editor and multi-file web submissions
- Automated judging reports specific submission errors
- Question bank and programming autograding
- Supports repeated submissions toward acceptance
Watch out
- No math autograding
- No written-work OCR
- No LMS or LTI support
- Submission client has no compatibility guarantee
Who it suits
Kattis suits learners, recruiters and competition organizers who need automated programming submissions and coding challenges. It is less suitable for math grading, OCR-based written work or LMS/LTI integration.
Verdict
Kattis provides a focused environment for submitting and automatically judging programming solutions. Review the client requirements and account rules if your workflow depends on local tooling or shared accounts.
The facts
Each one read from Kattis's own pages, with the date it was checked.
What it does
- Account access
- Accounts can be accessed with a username and password or through third-party authentication services.checked 7 Oct 2026
- Account limit
- Personal accounts are individual and may not be shared; Kattis says each person may have only one personal account.checked 7 Oct 2026
- Automated judging
- Kattis compiles or syntax-checks submissions, runs them against test cases, and reports errors such as wrong answer, time limit exceeded, or runtime error.checked 8 Oct 2026
- Client requirements
- The submit client requires Python 2 or 3 and the requests library, and Kattis provides it as-is without guaranteeing it will work on a given system.checked 8 Oct 2026
- Competition use
- Kattis is used in the ICPC world championships and other programming competitions.checked 8 Oct 2026
- Customer content
- Kattis’s terms say users retain ownership of submitted content but grant Kattis a transferable, royalty-free, non-exclusive, non-revocable right to store and use it.checked 7 Oct 2026
- Judging
- Kattis compiles or syntax-checks submissions, executes them against test cases, and reports errors such as wrong answer, time limit exceeded, or runtime error.checked 7 Oct 2026
- Product
- Kattis is an online service provided as software as a service.checked 7 Oct 2026
- Python client requirements
- The submission client requires Python 3 and the requests and lxml libraries.checked 7 Oct 2026
- Recruiting use
- Kattis automatically screens and evaluates applicants’ programming skills with coding challenges.checked 8 Oct 2026
- Recruiting workflow
- Companies can challenge developers before the recruitment process, add coding challenges to job pages, or use quality tests later in recruitment.checked 8 Oct 2026
- Repeated submissions
- Users can submit a solution multiple times to test their way to an accepted solution.checked 8 Oct 2026
- Security
- Kattis’s privacy policy lists encryption, pseudonymisation, access controls, access logs, secure network, VPN, firewall, backups, regular security inspection, and two-step verification among its security measures.checked 7 Oct 2026
- Submission client
- Kattis provides a Python 3 submission client that submits code through its website.checked 7 Oct 2026
- Submission client limitation
- Kattis says it provides the submission client as-is and does not guarantee that it will work on a user’s system.checked 7 Oct 2026
- Submission methods
- Code can be submitted through a web form or a submit client; the form supports multiple files.checked 8 Oct 2026
- Support
- Kattis’s support site offers a knowledge base and a form for submitting support tickets.checked 8 Oct 2026
- Supported language guidance
- The knowledge base includes programming-language help for languages including C, C++, Java, JavaScript, Julia, Kotlin, Python, and Scala.checked 8 Oct 2026
- Testing limitation
- Users can test against provided sample data or their own data, but must submit to Kattis to check whether it will accept a solution.checked 8 Oct 2026
- Use cases
- Kattis’s privacy policy describes its services as educational and recruiting services.checked 7 Oct 2026
Where it runs
- Browser submissions
- Users can write code in a browser editor or upload code from their computer.checked 7 Oct 2026
The company
- Company identity
- Kattis’s terms identify the provider as Kattis AB, a Swedish corporation.checked 7 Oct 2026
- Headquarters
- Stockholm, Swedenchecked 28 Sep 2026
Alternatives to Kattis
- 1
CodeSignal
Free planAndroidiOSWebAPI8.2From $24.99 a month - 2
HackerEarth Assessments
Free planAndroidiOSWebAPI8.2From $99 a month - 3
CodeChef IDE
Free planWebAPI7.4From $124 a year - 4
HackerRank
WebAPImacOSWindows7.4From $165 a month - 5
Codility
WebAPImacOSWindows7.3From $1,200 a year - 6
CSSBattle
Free planWeb6.7From $4.90 a month