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Use Case · System Design Interviews

Stay structured in a
system design interview.

The calm way to handle an open ended design round. When the prompt lands, one shortcut and Hidini reads your screen, then surfaces the framework to follow, the capacity math to state, and the tradeoffs to weigh. Invisible on screen share.

One prompt in. A plan out.

From a blank canvas to a clear plan

Design rounds are open ended on purpose. It is easy to ramble, easy to sink into one corner, and easy to forget a whole dimension while the clock runs. Hidini reads the prompt and hands back the arc to follow, so you sound organized from the first sentence.

The panel stays invisible on the shared screen. You keep the pen and do the talking.

Hidini
reading prompt

Design a URL shortener

  1. 1

    Clarify: read/write ratio, latency target, custom aliases, expiry

  2. 2

    Estimate: 100M new links/day, about 1.2K writes/s, 10:1 reads

  3. 3

    High level: write API, hash service, key/value store, cache, CDN

  4. 4

    Deep dive: base62 keys vs a key generation service

  5. 5

    Scale: consistent hashing, read replicas, cache the hot keys

  6. 6

    Tradeoffs: SQL vs NoSQL, sync vs async analytics

  7. 7

    Bottlenecks: hot links, cache stampede, single points of failure

How It Works

Prompt to plan in seconds

  1. Press one shortcut

    A single hotkey wakes Hidini. No window to find, no tab to switch to, nothing the interviewer can see on the shared screen.

  2. It reads the prompt

    Hidini captures the design question on your screen, whether it is a doc, a whiteboard, or a chat message, and works out what the round is really asking.

  3. A structured plan appears

    Back comes a framework to follow, the capacity math to state, and the tradeoffs to weigh, so you lead the conversation instead of freezing on it.

Why It Fits

Made for open ended design rounds

  • Invisible on screen share

    Hidini does not appear in shared or recorded screens on macOS, so a quick glance for structure stays yours.

  • A framework, so you never ramble

    Requirements, estimates, high level design, deep dive, tradeoffs, bottlenecks. Every round follows the same clear arc.

  • Capacity math without the panic

    Back of the envelope numbers on tap, so requests per second and storage estimates come out clean under pressure.

  • Every dimension covered

    Scalability, availability, consistency, latency, the data model, and failure modes, none of them forgotten.

  • Ready for the curveball

    When the interviewer says scale it to ten times the traffic, the next move is already in front of you.

  • Quiet, not distracting

    The nudge stays out of the way, so you keep talking through your reasoning instead of going silent.

FAQ

Questions, answered

Can the interviewer see Hidini during a system design interview?

No. Hidini is invisible to screen sharing and screen recording on macOS. On the shared screen there is nothing to spot, so a glance for the next dimension to cover never shows up on the call.

Does it work for any design prompt?

Yes. Hidini reads the prompt on your screen and adapts, whether the round is a URL shortener, a news feed, a chat system, a rate limiter, or something the interviewer made up on the spot.

Will it just hand me the whole answer?

It is built to keep you in the driver seat. Hidini surfaces the structure, the estimates, and the tradeoffs to raise, so you still explain and defend the design in your own words.

Does it help with the capacity estimation math?

Yes. It surfaces the back of the envelope numbers for the prompt, so requests per second, storage, and bandwidth estimates are ready when the interviewer asks for them.

Prepping the coding round too? See AI assistance during coding interviews or read about every feature.

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