System Design readiness pathFree assessment

System Design Interview Readiness

Find decision gaps, strengthen your architectural judgment, and verify it across fresh scenarios.

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Content reviewed Jul 20, 2026
Sample readiness report

See your decision gaps before you practice

Take a free assessment to identify the tradeoffs weakening your design answers and the next decision worth repairing.

Sample readiness result68 / 100

See which interview decisions are strong and where your reasoning needs work.

Sample top gapWrite-path correctness under retries

Targeted repair: Strengthen durable event publication and idempotent processing.

ReportDecision gapsPass PlanTargeted repairsUnlocksDecision Drills + Readiness Exam
01Answer system design scenarios
02Work your Pass Plan
03Complete the Readiness Exam
See it in action

Watch CramHQ turn one missed tradeoff into a defensible design decision.

CramHQ

Find the weak decision. Strengthen the design.

Watch one missed tradeoff become a defensible architecture decision.

How CramHQ finds the tradeoff weakening your design

Interview scenario

Practice making the architecture decision, not reciting a pattern.

Sample question Write-path correctness

An orders API commits an order, then publishes an OrderCreated event. Broker outages sometimes leave committed orders without events. Which design best closes this gap?

  • Retry event publication in the request until the broker accepts it.
  • Write the order and an outbox record in one database transaction, then publish the outbox asynchronously.Correct
  • Publish the event first, then write the order after the broker acknowledges it.
  • Increase broker retention so missing events remain available longer.
Why this is the answer

The decision turns on atomic durability across the database write and publication intent. A transactional outbox records both together, while an asynchronous publisher can retry safely after broker recovery.

Interview readiness path

Assess your judgment, strengthen it, then validate it.

Start with an initial readiness report, repair the decisions holding you back, build breadth through Decision Drills, and finish with the System Design Readiness Exam.

01
Assessment

Get an initial readiness report and the decision gaps most worth repairing.

02
Repair and drill

Strengthen weak decisions, then build breadth through focused Decision Drills.

03
Readiness Exam and final report

Complete the Decision Drills and Readiness Exam to produce a full-path readiness signal.

Interview decision coverage

Practice the decisions strong system design interviews demand.

Practice emphasis spans requirements, estimation, APIs and data, communication, caching, write paths, partitioning, consistency, reliability, performance, observability, security, cost, migration, specialized systems, and end-to-end synthesis.

Interview Framing and Requirements

8% practice emphasis

15 decision areas

Capacity Estimation and Constraint Translation

7% practice emphasis

18 decision areas

API, Data Model, and Access Patterns

7% practice emphasis

18 decision areas

Service Communication, Edge, and Traffic Management

4% practice emphasis

15 decision areas

Read Path Design and Caching

7% practice emphasis

15 decision areas

Write Path Design and Async Processing

8% practice emphasis

18 decision areas

Partitioning, Sharding, and Hotspot Management

7% practice emphasis

15 decision areas

Consistency, Correctness, and Concurrency Control

8% practice emphasis

21 decision areas

Reliability, Failure Handling, and Degradation

8% practice emphasis

18 decision areas

Performance, Latency, and Tail Behavior

7% practice emphasis

15 decision areas

Observability, SLOs, and Operations

8% practice emphasis

15 decision areas

Security, Abuse, Privacy, and Permissions

3% practice emphasis

18 decision areas

Cost, Complexity, and Operational Tradeoffs

4% practice emphasis

15 decision areas

Migration, Rollout, and Evolution

3% practice emphasis

15 decision areas

Specialized System Patterns and Data Structures

3% practice emphasis

24 decision areas

System Design Synthesis and Challenge Handling

8% practice emphasis

15 decision areas

Decision Drills after assessment

See what the Decision Drills unlock after your assessment.

Take the assessment first so CramHQ can connect each Decision Drill to your readiness report and Pass Plan.

16 Decision Drills

Strengthen one part of the interview loop at a time, then review the reasoning behind each tradeoff.
01Decision Drill

Requirements and Scope

Turn ambiguous prompts into explicit requirements, constraints, scope boundaries, and useful clarifying questions.

Scenarios15TimerOptional
Start assessment first
02Decision Drill

Capacity and Constraint

Estimate traffic, concurrency, storage, bandwidth, fanout, compute, and connection limits so scale assumptions drive the design.

Scenarios18TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

03Decision Drill

API, Data Model, and Access Pattern

Choose API boundaries, sources of truth, indexes, schemas, and storage models from concrete read and write patterns.

Scenarios18TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

04Decision Drill

Service Communication and Traffic

Decide where protocols, gateways, proxies, load balancing, routing, health checks, and failover belong.

Scenarios15TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

05Decision Drill

Read Path and Caching

Balance latency and freshness with cache placement, invalidation, CDNs, read models, and hot-key controls.

Scenarios15TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

06Decision Drill

Write Path and Async Processing

Design synchronous and asynchronous boundaries, queues, workers, retries, dead-letter handling, backpressure, and reliable event publication.

Scenarios18TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

07Decision Drill

Partitioning and Hotspot

Choose partition and sharding keys, detect hot partitions, and rebalance without breaking locality or tenant isolation.

Scenarios15TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

08Decision Drill

Consistency and Concurrency

Protect invariants with consistency models, state machines, idempotency, concurrency control, transactions, sagas, and replication coordination.

Scenarios21TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

09Decision Drill

Reliability and Degradation

Handle dependency, overload, and regional failures with admission control, graceful degradation, replay, restore, and disaster recovery.

Scenarios18TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

10Decision Drill

Performance and Tail-Latency

Trace critical paths and reduce tail latency through precomputation, bounded fanout, parallelism, and queueing control.

Scenarios15TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

11Decision Drill

Observability and Operations

Define useful SLOs and connect metrics, saturation, logs, traces, alerts, incident response, and repair verification.

Scenarios15TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

12Decision Drill

Security, Abuse, and Privacy

Place authentication and authorization correctly while designing rate limits, anti-abuse controls, isolation, data lifecycle protection, and secure operations.

Scenarios18TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

13Decision Drill

Cost and Operational Tradeoff

Identify dominant cost drivers and justify managed services, operational ownership, phased complexity, and build-versus-buy decisions.

Scenarios15TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

14Decision Drill

Migration and Rollout

Plan compatibility, phased rollout, backfills, reindexing, dual writes, cutovers, rollback, and recovery without losing correctness.

Scenarios15TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

15Decision Drill

Specialized Systems

Apply the right patterns for collaboration, search, geospatial, media, time series, ranking, approximate structures, IDs, and rate control.

Scenarios24TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

16Decision Drill

System Design Synthesis

Identify the highest-leverage repair, preserve requirements, defend tradeoffs, handle ambiguity, and connect decisions across the full design.

Scenarios15TimerOptional

Start with the free assessment; full access unlocks this Decision Drill.

Final readiness check

Validate the full interview loop under time.

Use this after the Decision Drills to validate system design judgment, pacing, and breadth.

FinalReadiness exam

System Design Readiness Exam

Use this after the Decision Drills to check system design judgment, pacing, and breadth.

Scenarios30Time1 hrModeTimedReadiness target80 / 100
Start assessment first

Start with the free assessment; full access unlocks the System Design Readiness Exam.

Decision formats

Practice the ways interview tradeoffs are tested.

Each scenario asks you to rank architecture choices against explicit constraints, either as one strongest decision or a set of decisions that must work together.

Single answer

Choose the strongest design under the stated constraints.

Multi-answer

Identify the decisions that must work together to satisfy the scenario.

Content integrity

Original scenarios, aligned to system design decision areas.

CramHQ helps you practice defensible architecture decisions across realistic interview constraints and failure modes.

Decision practiceOriginal scenarios

Original system design scenarios aligned to realistic interview decision areas.

Coverage sourceInterview decision areas

Coverage is checked across requirements, scale, data, correctness, reliability, operations, and system evolution.

Learning goalDefensible judgment

Built by CramHQ for system design interview preparation.