System design practice
Pick a prompt, write the design the way you would at a whiteboard, and get it graded against the same six dimensions every time — so scores are comparable across attempts. The grading runs on your own Claude API key, called directly from this page. Background reading: the system design posts.
API key — not set
This tool calls the Claude API from your browser with your own key. The key is never sent to this site, stored on any server, or logged — it goes straight to api.anthropic.com. It is held in this tab's session storage unless you ask to keep it. Use a key you can rotate, and clear it when you're done.
Design a service that turns a long URL into a short one and redirects visitors to the original. Users can optionally pick a custom alias and see click counts.
100M new links/day, 10B redirects/day, links live for 5 years.