How to practice for a system design interview?

The best way to practice system design is by simulating real-world architectures. MockArch provides an interactive system design simulator where you can construct cloud architectures, simulate real-time traffic, estimate infrastructure costs, and on Pro get LLM deep analysis on your design choices.

How does MockArch AI feedback work?

On Pro, deep LLM analysis evaluates your design for bottlenecks, scaling issues, and security, with a monthly usage cap per subscriber (quota resets at 00:00 UTC on the first day of each calendar month). You receive concrete recommendations for improvements. Free tier includes automated rule-based checks.

Can I cancel my MockArch Pro subscription anytime?

Yes. The Pro tier is billed month-to-month with no long term contracts. You will retain access to Pro features until the end of your billing cycle.

What are the core concepts of system design?

Core concepts include scalability (horizontal vs vertical), load balancing, caching strategies, database sharding, CAP theorem, and microservices architecture. MockArch helps you practice and visualize all these components interactively.

How to choose between SQL and NoSQL in a system design interview?

Choose SQL for structured data with complex relationships and ACID compliance requirements. Choose NoSQL for unstructured data, horizontal scalability, and rapid schema iteration. Use MockArch's simulator to compare the performance and cost tradeoffs of both.

How do load balancers work in system architecture?

Load balancers distribute incoming network traffic across multiple servers to ensure no single server bears too much demand, improving responsiveness and availability. In MockArch, you can drag and drop load balancers to see how they impact your system's bottleneck limits.

What is the best way to prepare for FAANG system design interviews?

The most effective preparation combines reading foundational texts (like Designing Data-Intensive Applications), practicing whiteboard problems, and using interactive simulators like MockArch. Pro includes deep LLM analysis to complement your practice; the free tier includes rule-based checks and simulation.

Can I estimate AWS cloud infrastructure costs?

Yes. MockArch acts as a dynamic infrastructure cost calculator. As you add databases, compute instances, and define traffic volumes, the simulator provides a real-time estimation of your monthly cloud spend.

AI System Design Interview Simulator

Practice system design interviews,
not just diagrams.

Use an AI system design interview simulator to reason through architecture tradeoffs, model infrastructure costs, and test scalability with senior-level feedback.

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stacksScenario library (easy free; full on Pro)

paymentsLive cost & traffic simulation

psychologyAI deep analysis (Pro)

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Architecture Score

Single Point of Failure

Detected at Load Balancer L1

Estimated Infra Cost

$14,200 /mo

Latency Metrics

A system design practice platform for architecture interview prep

schema

Practice distributed systems design

Build system design interview answers with APIs, queues, databases, caches, and precise relationship mapping for throughput and read/write ratios.

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Simulate scale, latency, and cost

Identify bottlenecks before the interview. Estimate cloud infrastructure cost, multi-region data transfer, and latency tradeoffs at high scale.

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Get AI system design feedback

Get instant feedback on single points of failure, data consistency risks, database sharding choices, load balancing, and over-engineering.

“Your use of Cassandra for this transactional workload may lead to tombstone issues during heavy deletions...”

Choose a system design interview question

Select high-scale distributed systems like Uber-lite, global chat, video ingestion, or high-throughput payment gateways.

Build and simulate the architecture

Drag and drop components, map data flows, and run the system design simulator to see latency metrics and cost estimates.

Review AI feedback and iterate

Analyze AI feedback, refine your architecture interview answer, and watch scores change as you resolve bottlenecks.

AI Analysis Reportv4.2.0-stable

Reliability

92%

Scalability

98%

error

Potential Over-engineering

Kubernetes for a simple worker tier might be excessive; consider Serverless if load is bursty.

warning

Consistency Risk

Your Redis cache layer lacks a TTL strategy for the Auth tokens, leading to staleness.

Instant AI Review of your technical architecture

Stop guessing if your design scales. Our model is trained on thousands of staff-level design documents and real-world post-mortems.

check_circleDetects single points of failure
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check_circleScores scaling, cost, and resilience
check_circleRecommends next-step improvements

Advanced Scenario Previews

Complex systems designed for senior and staff engineer candidates.

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Advancedhub

Multi-region Chat Platform

Solve for consistency, global latency, and edge compute for 10M+ DAU.

schedule60mstar4.9

Intermediatepayments

Event-driven Payments

Implement exactly-once processing and distributed transactions.

schedule45mstar4.8

Advancedvideocam

Video Ingestion Pipeline

Handle heavy throughput, transcoding, and content delivery strategies.

schedule90mstar5.0

Corenotifications

Scale Notification System

Design a robust pub/sub model for multi-channel messaging.

schedule30mstar4.7

Your system design edge starts here

Start free, then upgrade for every scenario difficulty, AI deep analysis, and unlimited saved designs.

Free

₹0/mo

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checkFull component palette
checkReal-time cost & traffic simulation
checkRule-based standard analysis (automated checks)
checkEasy interview scenarios (timed practice & scoring)
checkExport canvas as image

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Pro

₹299/mo

check_circleEverything in Free
check_circleUnlimited saved designs
check_circleAll scenario difficulties (medium & hard unlocked)
check_circleUp to 20 AI deep analyses per calendar month (UTC). Resets at 00:00 UTC on the first day of each calendar month.
check_circleExport as PNG & JSON
check_circlePriority support

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System Design Interview FAQ

Common system design interview questions

How do I practice system design interviews online?

Start with a realistic system design interview question, build the architecture, explain tradeoffs, and review feedback. MockArch combines a diagram canvas, traffic simulation, cost estimates, and AI feedback so practice feels closer to a real senior engineering interview.

What makes MockArch a system design interview simulator?

MockArch lets you model APIs, databases, caches, queues, load balancers, traffic volume, latency, and cost. Instead of only drawing boxes, you can test whether the architecture handles scale and then improve it based on scoring and feedback.

Do I need a credit card to start?

No. Sign up and use the free tier, including up to 3 saved designs, easy scenarios, rule-based analysis, cost and traffic simulation, and export as image without a card. LLM deep analysis requires Pro.

Can I cancel anytime?

Yes. Pro is month-to-month. Cancel anytime and you keep access until the end of your billing period. No long-term contract.

What's included in the free tier?

Up to 3 saved designs, full component palette, cost and traffic simulation, rule-based standard analysis, easy interview scenarios with scoring, and export as image. Medium and hard scenarios, unlimited saved designs, and LLM deep analysis up to 20 per UTC calendar month on Pro require Pro.

How is MockArch different from Miro or Excalidraw?

Those are diagram tools. MockArch is built for system design interview prep: you get real-time cost estimates, load simulation, and on Pro, AI feedback that scores your design and suggests improvements like a staff engineer in the room.

Is my data secure?

Designs are stored securely. We use secure payment processing. We do not sell your data. You can export and delete your work anytime.

How does AI feedback work?

Pro includes Up to 20 AI deep analyses per calendar month (UTC). Resets at 00:00 UTC on the first day of each calendar month. You get feedback on bottlenecks, scaling, security, and concrete improvements. Free tier includes automated rule-based checks only.

Still have questions? Explore system design interview practice or start free and see for yourself.

Walk into your next system design interview with real reps behind you.

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Practice system design interviews, not just diagrams.