Open source
Chat-only practice with an AI interviewer: JavaScript (default tab), TypeScript, React, Node.js, NestJS, Next.js, MongoDB, PostgreSQL, system design, software architecture, and design patterns. Provide your own LLM API key on the Settings page — it is encrypted with a passphrase you choose and stored only in this browser. Deep links: ?track=system_design, ?track=nextjs, etc. With no query string, the first tab (JavaScript) is selected.