▸case-01 We are building a multi-tenant SaaS application that serves both web dashboards and native mobile applications with vastly different payload requirements. Please outline a Backend-for-Frontend (BFF) architecture and API gateway setup. Deliver endpoint contract specifications, describe the authentication flow and rate-limiting strategy, detail background processing and caching invalidation workflows, and include a deployment rollout plan and testing strategy. | fail→pass | 45,751 | 39,724 | -13% | 1 | 1 | 0% | 8,265 | 10,840 | +31% | 0 | 0 | — |
▸case-02 We are designing a real-time document collaboration platform requiring low-latency client updates alongside standard management operations. Please construct a microservices architecture plan that defines bounded contexts, specifies data contracts for both REST endpoints and streaming protocols, lays out connection failure handling and fallback mechanisms, details centralized logging and metric tracking, and presents technology recommendations with rationale. | pass→pass | 44,855 | 38,080 | -15% | 1 | 1 | 0% | 8,256 | 10,226 | +24% | 0 | 0 | — |
▸case-03 We are building an e-commerce platform where order creation spans inventory reservation, payment processing, and shipment allocation across separate services. We want to avoid 2PC distributed database locking. Outline an asynchronous transaction pattern for order fulfillment, including API contracts, failure compensation steps, and state tracking. | pass→pass | 30,903 | 24,040 | -22% | 1 | 1 | 0% | 6,010 | 8,693 | +45% | 0 | 0 | — |
▸case-21 Since we are designing the backend order processing service, please generate the complete PostgreSQL DDL create table statements, foreign key relationships, and B-Tree index creation scripts for orders and line items. | fail→fail | 22,026 | 17,328 | -21% | 1 | 1 | 0% | 4,414 | 7,229 | +64% | 0 | 0 | — |
▸case-04 Our enterprise backend is a monolithic Ruby on Rails application handling payments, user profiles, and reporting. The team wants to extract the high-traffic payment module into a standalone microservice without risking zero-downtime operations or a high-risk big-bang rewrite. Outline a service migration architecture and traffic routing strategy. | pass→pass | 25,771 | 27,806 | +8% | 1 | 1 | 0% | 4,280 | 8,051 | +88% | 0 | 0 | — |
▸case-05 Our platform sends instant user notifications (SMS, Push, Email) triggered by system events like password resets and billing alerts. Direct REST calls during checkout peaks are causing request timeouts. Design a resilient backend messaging architecture to decouple event producers from notification delivery workers. | pass→pass | 22,003 | 25,783 | +17% | 1 | 1 | 0% | 3,740 | 8,406 | +125% | 0 | 0 | — |
▸case-06 We are migrating multiple REST APIs to a unified GraphQL federated gateway. Our mobile team complains that querying nested user orders causes dozens of redundant downstream database/API queries per request. Design the GraphQL schema federation structure and query execution strategy to prevent performance degradation. | fail→fail | 23,794 | 30,143 | +27% | 1 | 1 | 0% | 4,013 | 9,127 | +127% | 0 | 0 | — |
▸case-07 We are building a payment gateway API that sends event webhooks to third-party merchant servers. Merchants complain about receiving duplicate notifications during network glitches, and engineering wants to verify webhook payload authenticity. Design an external webhook delivery and processing architecture. | pass→pass | 22,932 | 28,944 | +26% | 1 | 1 | 0% | 3,839 | 8,804 | +129% | 0 | 0 | — |
▸case-08 Our API platform needs to enforce rate limits (100 requests per minute per tenant) across 20 horizontally autoscaled gateway nodes. Local instance memory cannot keep state synchronized. Design a distributed rate limiting architecture. | pass→pass | 21,194 | 29,467 | +39% | 1 | 1 | 0% | 3,377 | 8,549 | +153% | 0 | 0 | — |
▸case-09 Our microservices architecture consists of 15 services communicating via REST and gRPC. When an API call fails deep in the call chain, engineers spend hours matching disparate logs. Design an observability framework to trace requests end-to-end across service boundaries. | fail→pass | 18,575 | 28,349 | +53% | 1 | 1 | 0% | 3,292 | 8,737 | +165% | 0 | 0 | — |
▸case-10 Our internal microservices exchange heavy data payloads thousands of times per second. JSON serialization overhead and HTTP/1.1 head-of-line blocking are bottlenecking throughput. Design a high-performance inter-service communication layer with strict contract definitions. | pass→pass | 33,403 | 33,816 | +1% | 1 | 1 | 0% | 5,705 | 9,715 | +70% | 0 | 0 | — |
▸case-11 Our checkout service depends on a slow third-party address validation API. When the third-party API slows down from 200ms to 15s, our checkout service thread pool exhausts, crashing the entire web application. Design a resilience pattern architecture to isolate failures and degrade gracefully. | pass→pass | 18,150 | 21,458 | +18% | 1 | 1 | 0% | 2,869 | 7,392 | +158% | 0 | 0 | — |
▸case-12 Our financial platform performs millions of transactional writes per hour. Business intelligence needs complex multi-dimensional analytical queries on real-time balances without slowing down core transactional writes. Design a data architecture pattern separating read and write workloads. | pass→pass | 20,211 | 26,008 | +29% | 1 | 1 | 0% | 3,117 | 7,994 | +156% | 0 | 0 | — |
▸case-13 We are designing a multi-tenant enterprise B2B backend architecture where corporate clients require fine-grained role-based access control (RBAC) and service-to-service zero-trust security. Design an end-to-end authentication and authorization architecture. | fail→fail | 46,560 | 39,007 | -16% | 1 | 1 | 0% | 8,241 | 10,446 | +27% | 0 | 0 | — |
▸case-14 We are building a real-time live trading dashboard where thousands of clients connect via WebSockets. When we scale from 1 server instance to 10 instances, messages broadcast by server 1 fail to reach users connected to server 2. Design a horizontally scalable WebSocket architecture. | fail→pass | 23,241 | 23,172 | -0% | 1 | 1 | 0% | 3,581 | 7,588 | +112% | 0 | 0 | — |
▸case-15 Mobile clients on unstable networks frequently experience request timeouts during credit card checkout. Users re-tap the pay button, resulting in duplicate charges. Design an idempotent payment API endpoint contract and processing flow. | pass→pass | 20,178 | 29,118 | +44% | 1 | 1 | 0% | 3,377 | 8,792 | +160% | 0 | 0 | — |
▸case-16 We are redesigning our public API's response structure to replace flat user fields with nested object hierarchies. Hundreds of external developer clients rely on the current v1 endpoints. Design an API versioning and deprecation strategy that prevents breaking existing integrations. | pass→pass | 19,843 | 26,148 | +32% | 1 | 1 | 0% | 3,588 | 8,356 | +133% | 0 | 0 | — |
▸case-17 Our media processing platform allows users to upload raw 4K videos for multi-format encoding. Encoding takes between 2 to 10 minutes. Holding open HTTP connections causes client timeout errors and gateway pool exhaustion. Design an asynchronous task processing API workflow. | pass→pass | 22,272 | 28,746 | +29% | 1 | 1 | 0% | 3,907 | 9,028 | +131% | 0 | 0 | — |
▸case-18 Our e-commerce homepage product catalog receives 50,000 requests per second. When the main Redis cache key for top products expires, thousands of concurrent backend threads hit the database simultaneously, causing database crashes. Design a resilient multi-layer caching architecture that prevents cache stampedes. | pass→pass | 25,008 | 27,533 | +10% | 1 | 1 | 0% | 4,208 | 8,264 | +96% | 0 | 0 | — |
▸case-19 Our microservices platform handles mission-critical financial transactions 24/7. Engineering needs to deploy continuous updates with zero downtime and automated rollback capabilities if error rates spike. Design a continuous deployment and traffic management strategy. | pass→pass | 21,515 | 28,041 | +30% | 1 | 1 | 0% | 3,462 | 8,244 | +138% | 0 | 0 | — |
▸case-20 Our social feed service queries millions of user posts. Offset-based pagination (`LIMIT 20 OFFSET 100000`) is causing severe database performance degradation as users scroll deep. Design an API pagination architecture optimized for deep scrolling and real-time feeds. | pass→pass | 22,781 | 30,720 | +35% | 1 | 1 | 0% | 3,795 | 9,122 | +140% | 0 | 0 | — |
▸case-22 We are building an e-commerce dashboard. Please write the React TSX components with Tailwind CSS styling for the order listing page and responsive sidebar navigation. | fail→fail | 33,694 | 36,533 | +8% | 1 | 1 | 0% | 7,762 | 12,054 | +55% | 0 | 0 | — |
▸case-23 We need the backend infrastructure running on AWS. Please provide the complete Terraform HCL module to provision the VPC, public/private subnets, NAT Gateways, and EKS cluster node pools. | fail→fail | 34,632 | 30,768 | -11% | 1 | 1 | 0% | 8,228 | 10,746 | +31% | 0 | 0 | — |