The Only App You Must Use to Give System Design Interviews

System design interviews are controlled chaos. You are thinking on your feet, turning a fuzzy problem statement into a coherent architecture, and narrating your reasoning in real time. The quicker you can get your ideas on the screen, the more time you have to iterate and answer follow-up questions. That is why Presentify is my go-to tool for remote system design interviews on a Mac.

Presentify is a lightweight Mac menu bar app that lets you draw on anything on your display: the interview prompt, a shared doc, a slide, or a blank whiteboard. Rectangles, arrows, text labels and freehand ink are all a keyboard shortcut away, so the diagram grows alongside the conversation.

Why Presentify Works for System Design Interviews

• A whiteboard anywhere: press ⌃A to start annotating, then W to switch to a clean whiteboard, or draw directly on top of the prompt or the coding pad.
• Clean shapes and arrows: R draws rectangles for services and databases, A draws arrows for data flow, and holding Shift keeps lines straight and shapes square or round. Hold Option while drawing a rectangle or circle to fill it with a semi-transparent color.
• Quick labels: press T for text to label an API gateway, a cache or a queue. Scroll over a label to change its size, and press Esc to go back to free hand.
• Fix mistakes without starting over: ⌘Z undoes the last stroke, and holding ⌘ lets you select specific items to delete, so you can swap one component without wiping the diagram.
• Light on resources: Presentify is a native macOS app that uses little memory, so your screen share stays smooth even on a modest laptop.

How I Use Presentify During a Live Interview

1. Sketch a scaffold first: in the first minute, I draw three rows of rectangles for the client, service and data tiers. It gives me a skeleton I can extend as requirements come in.
2. Narrate while drawing: as I describe the request flow, I trace arrows and type component names ("Auth Service", "Kafka Topic", "Redis Cache"). The interviewer sees my thinking as I say it.
3. Show alternatives in a second color: when asked about scaling read traffic, I switch colors with the number keys (1 to 5 are your favorite colors) and draw the change, such as a load balancer and read replicas, next to the original design. The contrast makes it obvious what changed.
4. Call out trade-offs: to flag a bottleneck, I hold Option to drop a translucent red box over the component and add a short note like "Single AZ" or "Hot partition". It keeps the discussion anchored to the diagram.

Pro Tips

• Share your whole screen. Annotations only show up for the interviewer when you share the entire screen (or the screen area) rather than a single window.
• Map tools to a Stream Deck. Almost every Presentify action has a shortcut you can customize, so rectangle, arrow, text and color keys can each be one tap away.
• Use macOS Focus to silence notifications during the interview.
• Keep a color convention, for example blue for core components, orange for async processing and green for optimizations, and set them as your five favorite colors.
• Press S at the end to save a screenshot of the final diagram for your own notes.

When You Don't Need It

Many interview platforms include a shared whiteboard, and some interviewers will ask you to use theirs. In that case, use the tool they provide. Presentify is most useful when you're sharing your own screen and want to draw on top of whatever is already there, or when the built-in whiteboard is clumsy. If you prefer drawing a finished diagram rather than sketching live, see our comparison of diagramming apps for Mac.

Ready to Streamline Your System Design Story?

The hardest part of a system design interview is keeping the interviewer aligned with your mental model. Presentify bridges that gap by turning your screen into a living diagram that you can refine on the fly. Practice with it a couple of times before the real interview so the shortcuts become automatic.

• Website: presentifyapp.com
• Mac App Store: Presentify, $14.99 one-time in the US, requires macOS 13 or later

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Note: First published in October 2025 and updated in October 2026. Features and prices are current as of October 2026 and can change; verify them on each official site before buying.

Disclosure: Presentify is made by Softal, the same company behind Apps.Deals.