In a system-design interview, the diagram supports what you say. The interviewer follows your explanation: why a cache sits in front of the database, what an arrow promises, and what happens when a request fails. Time spent lining up boxes and rerouting arrows is time not spent on that explanation.
Grind is built so your practice goes into the explanation. You talk through the design, and Lycana draws it.
What you practise when you talk
Saying a design aloud exposes gaps that a drawing can hide. A box labelled "Cache" looks complete. Saying "put a cache in front of the links database for redirects" invites the next question straight away: what happens on a miss, and how stale can a redirect be?
That is the habit an interview rewards: stating a decision, then the reason and the cost in the same breath. Practising by talking makes you do that every time you add something, not only when an interviewer stops you.
How what you say becomes a diagram
Grind runs on Lycana, which turns spoken or typed instructions into structured, editable diagrams. On Grind's design steps you use the same command bar as Lycana's diagram app.
For example, on the URL shortener's high-level design you might say:
- "Add a client, a URL service, and a links database."
- "The client calls the URL service, which reads and writes the links database."
- "Put a cache between the URL service and the database for redirects."
These are illustrative; you can phrase your design however you would explain it. While you speak, a live preview shows the change. A pause to think does not interrupt you or end the attempt. If something lands wrong, say the correction or edit the diagram directly. The diagram stays yours to change.
On the written steps, such as the requirements, Lycana writes down what you say as clear points. It only records what you said. Asking it for "the functional requirements for a URL shortener" adds nothing, because the answer has to come from you.
Feedback on each step, while it is fresh
When a step is ready, check it. The feedback says what the step covered against the question's criteria. What it missed stays hidden until you ask, so you can look for it yourself first. Revise, check again, and move on when the step holds up.
For a URL shortener that might read: covered, how a short code maps to its original URL; missing, what happens when two customers choose the same code. That second point is a sentence you can now say, and the fix is one more thing to say out loud.
The same canvas outside the interview
Grind and Lycana share one account, one sign-in, and one Lycana Pro plan. The way you describe a design in Grind is the way you describe one in Lycana: the same commands, the same canvas. Lycana's diagram app is for the designs you explain at work, in design docs and reviews.
The skill carries over too. A design review asks the same questions as an interview, in a different order. Lycana's guide, Explaining a design out loud is a skill you can practise, walks through that with the same URL shortener.
Try it
Start with the URL shortener, or browse the questions. Reading questions and articles needs no account. Starting an attempt does. A Free account gets one free question, ever, from the offered junior or mid-level options; further practice requires Lycana Pro. See current plan details.
