Live help in the real round. Mock rounds before it.
OphyAI System Design has two modes. Live Copilot listens to your interviewer, reads your whiteboard, and tells you what to say and what to draw next. Mock round is a full system design mock interview on a built-in whiteboard, with a voice AI interviewer and a Scorecard at the end.
Premium plan, $59 a month with 500 credits. 30 credits a live session, 20 credits a mock round.
3 minutes into high-level design. Deep dives by 29:00.
They asked: How do you generate the short codes?
Add an ID allocator that hands ID blocks to the app servers.
Shown in blue on your designUnique 7-character base62 codes.
Built for software engineers at mid, senior and staff level, for the 45 to 60 minute system design round. Practice for an interview you have set up, and the plan you build carries into your live session.
Hears the interviewer, reads your whiteboard, and keeps one design plan up to date while you talk.
A full round with an AI interviewer and a whiteboard. It watches your board, pushes back, and grades every step.
A voice interviewer and a whiteboard. You finish with a Scorecard and 3 fixes.
The role, company, interview date and your resume. Add the job description and the question if you know them.
What to say, what to draw, and when to move on. End the session to see the review.
Live Copilot follows the round as it happens. It hears the question, sees what you drew, and keeps one design plan that grows with the conversation.
Press Hear the call and pick the meeting tab with its audio. Your own answers come in through your microphone, and you can type a question any time.
Watch the board reads the tab or window where you draw and keeps reading it as you go. For a paper sketch, scan a code and send a phone photo.
Requirements, estimates, API and data, a boxes-and-arrows diagram, deep dives to offer and trade-offs to name, all in one plan that updates as you talk.
A short, numbered answer for each question, in plain words you can say out loud. Ask for it shorter, with more detail, or with the why.
The next box or arrow to add, shown in blue on your design, so your board keeps up with your answer.
The one estimate that backs up your answer, such as requests per second or storage, with a short note on where it comes from.
The follow-ups you are likely to get next, each with a short answer, so a hard question does not stop you cold.
Shows which of the 6 steps you are on and how long you have spent, with a nudge when a step runs long. Pop out a small overlay to keep it next to your call.
End the session and your plan, answers and board snaps stay in the review, which scores the round on the same 7 skills as a mock.
Add the role, the company, the interview date and your resume. The job description, the design question and your whiteboard tool are optional; leave the question empty and Live Copilot picks it up from the call. Choose 45 or 60 minutes. The session opens on interview day, and you start it when the round starts.
Live Copilot and Mock round follow the same six steps. The times are targets for a 45 minute round and scale for 35 or 60 minutes. They are a guide, not a rule.
Ask who uses it, the must-have features and the scale. Say what is out of scope before you draw.
Size the load: requests per second, storage, bandwidth and the peak. These numbers drive the design.
Write the main API calls and the data model, with the keys and how the data is read.
Draw the main boxes and a clear path for every request, from the client to storage.
Go deep on the hardest parts, such as consistency, hot spots and failures. Offer one by about two thirds of the round.
Recap the design and name the trade-offs you made.
New to the format? Read our system design interview guide for how each step works.
Practice the whole round out loud, on a whiteboard, with an interviewer who follows up on what you draw.
Your board has one posts database behind the feed service. What happens to feed reads when an account with 10 million followers posts?
Compare building each feed when someone posts with building it when someone reads.
Every finished Mock round ends with a Scorecard.
The Scorecard is an AI estimate. The bar (80 for Senior) is OphyAI's own benchmark, not any company's hiring bar.
Classic prompts you can run as a Mock round, from Starter to Advanced. Add the job description to a live session and you also get a practice question built from it.
Paste the job description when you set up a live session, and a practice question for that role shows up first in your library.
The best practice is out loud, on a whiteboard, against a timer. Study a question first, then run it as a Mock round and see where your time went.
Live Copilot works next to the tools your interviewer picks.
On the web, share the meeting tab with its audio in Chrome or Edge. The desktop app hears the call through your computer's audio.
Live Copilot reads the board in the tab or window you pick for it. Tell it which tool you will use when you set up the session.
Scan a code with your phone and send a photo of your whiteboard or paper sketch. It lands in your feed and your design updates.
Give every new link an ID from a counter and encode it in base62.
One account and one credit balance. System Design is not in the iPhone or Android app.
| Feature | Web | Desktop app (Mac and Windows) |
|---|---|---|
| Live Copilot | Yes | Yes |
| Mock round | Yes | Your practice rounds are listed in the app and open in your browser |
| Hearing the call | Share the meeting tab with its audio, in Chrome or Edge | Hears your computer's audio |
| Reading the board | Pick the whiteboard tab or window, or send a phone photo | Pick the board to watch; Cmd/Ctrl + Shift + S snaps it |
| Overlay | A pop-out window, hidden only when you share a single tab or window | Left out of screen sharing by macOS and Windows, like the main window |
| Shortcuts | On-screen buttons | Cmd/Ctrl + Shift + A answers the last question, Cmd/Ctrl + Shift + O shows the overlay, Cmd/Ctrl + Shift + H hides everything |
| Version | app.ophyai.com | 1.0.10 or later, for Mac and Windows |
System Design is on the Premium plan only, for every account.
| Premium | $59 a month with 500 credits, or $566 a year |
|---|---|
| Live session | 30 credits |
| Mock round | 20 credits |
| Pro plan | Does not include System Design |
| Interview Passes and free trials | Not available for System Design |
Credits are shared with Interview Copilot, Coding Interview and the other tools. See pricing
A system design copilot is an AI assistant that helps you during a live system design interview. OphyAI Live Copilot listens to the interviewer on your call and reads your whiteboard from a shared tab or window, or from a phone photo. It keeps one design plan up to date and, for each question, gives you a short answer to say, what to draw next, the key number to mention and how to handle pushback.
Yes. A Mock round is a full practice round on a built-in whiteboard. A voice AI interviewer opens the round, listens to you through your microphone, asks follow-ups about what you drew and pushes back. You can ask for up to 3 hints. When you finish, you get a Scorecard.
Practice the way the round works: out loud, on a whiteboard, against a timer, with someone who asks follow-ups. Learn the six steps first, then work through the classic questions and drill the estimates step until it takes a few minutes. Our system design interview questions guide covers 18 classics with requirements, estimates, a diagram and deep dives, and our back of the envelope calculation guide covers the math. Then run full mock rounds. An OphyAI Mock round gives you a voice AI interviewer on a built-in whiteboard, up to 3 hints, and a Scorecard that shows your time on each step and 3 fixes for next time.
You pick 35, 45 or 60 minutes, and a level: Mid-level, Senior or Staff. You can pause, and the clock stops while you do. Each round uses 20 credits.
18 classic system design prompts: URL shortener, rate limiter for a public API, news feed, chat app, ride-hailing dispatch, payment ledger, video upload and streaming, web crawler, notification system, search autocomplete, file storage and sync, ticket booking with seat holds, real-time leaderboard, hotel reservations, food delivery tracking, distributed cache, metrics and alerting, and ad click aggregator. If you add the job description to a live session, you also get one practice question built from it.
Yes. Live Copilot reads the board you are asked to use, such as Excalidraw, Miro, CoderPad, Google Drawings or FigJam, as long as it is open in a tab or window you pick for it. For a paper sketch or a board you cannot share, take a phone photo by scanning a code. Mock rounds use OphyAI's own whiteboard, built on Excalidraw, so there is nothing to set up.
Zoom, Google Meet and Microsoft Teams. On the web, OphyAI hears the call when you share the meeting tab with its audio in Chrome or Edge. The desktop app for Mac and Windows hears the call through your computer's audio. You can always type a question if audio is not coming through.
It depends on what you share. In the desktop app, macOS and Windows leave the OphyAI window out of screen sharing. On the web, the small pop-out overlay is hidden from the other side only when you share a single tab or window. If you share your entire screen, it shows. Neither one hides from a webcam or a person in the room.
No. System Design is on the Premium plan only: $59 a month with 500 credits. A live session uses 30 credits and a mock round uses 20 credits. There are no Interview Passes or free trials for System Design.
Both modes work on the web. The OphyAI desktop app for Mac and Windows (version 1.0.10 and later) runs Live Copilot and lists your practice rounds, which open in your browser. System Design is not in the iPhone or Android app.
The Scorecard is an AI estimate of your round. It gives a score from 0 to 100, scores for 7 skills (Requirements, Estimates, API and data, High-level design, Deep dives, Trade-offs and Communication), your time on each step against a target, 3 fixes, your board next to a strong answer's board, and the moments that mattered. The bar shown for your level (80 for Senior) is OphyAI's own benchmark, not any company's hiring bar.
Start with a Mock round on the built-in whiteboard, then set up Live Copilot for interview day. System Design is on the Premium plan.
