Everything the product runs today, on one page. If what you need is not here, it is not here.
Languages
Questions can be set in JavaScript, TypeScript, Python, Java, Go and C++.
Interactive Run for JavaScript, TypeScript and Python; the rest compile on submit.
JavaScript, TypeScript and Python execute in the candidate's own browser — nothing to install, and no server to wait for.
Java, Go and C++ are compiled and graded on our servers when the candidate submits.
The standard library, in every one of them. Third-party packages do not resolve.
Web and frameworks
Web questions can be written in plain HTML/CSS/JS and React.
A web question is a set of files with index.html as its entry, and the preview re-renders as the candidate types.
The preview runs entirely in the candidate's browser: nothing executes on a server, and the page it renders has no network.
A candidate can import react and react-dom/client. There is no installer and no registry.
Web questions are not scored. A reviewer reads the submitted files and the rendered result.
How work is set
Live interviews, plus take-homes and challenges.
Take-homes and challenges are worked on alone, in the candidate's own time, from one link you send.
A live interview is you and the candidate in the same editor at the same time, with the code and the output shared.
Algorithm questions are checked against your expected output when the candidate submits. A question can be set to free run instead, with no automatic checking.
Every paste is recorded with its size, and every tab switch and return, on a timeline the reviewer reads beside the code.
Not supported
The list above is the whole of it. These are the things people ask for that we do not do.
Any language not named above. There is no setting that adds one.
Web frameworks other than those named above — Vue, Svelte and Angular do not run in a preview.
Installing packages. An algorithm question gets the standard library; a web question gets react and react-dom/client.
A score for a web question. The files and the rendered result go to a human, and nothing turns them into a number.
SSO, SAML and a signed DPA.
Proctoring. There is no webcam, no screen recording and no lockdown browser — work set from a link is unproctored by design, and the candidate is told so before they start.
Covers what you need?
Try it in the sandbox without an account, or read how the rest of it works.