PlayCloudBlocks
Practise AWS solution architecture on a canvas
Read a scenario, build the design, submit. You get a percentage against what the scenario actually requires, and a written review of what you built — what is accurate, what is wasteful, what is missing, and why in each case.
- Concurrency at scaleassociate
Clinic Appointment Booking
A healthcare company operates thousands of clinics, and patients book appointments through a mobile application. The system has a hard concurrency problem: two patients may try to book the final available slot at exactly the same moment, and only one booking can succeed. Traffic is ordinary for most of the day but becomes extreme when appointments for popular doctors are released. The company wants a serverless architecture and does not want to manage database servers. Appointment data must remain durable and the system should scale automatically.
Build from scratchMultiple choiceFill the gaps - Consistency and transactionsassociate
Banking Transaction Processing
A financial application processes millions of account transactions every day. A single transaction moves money from one account to another, and the system must guarantee that money is never lost or duplicated. Multiple requests may attempt to update the same account at the same time, and a transfer must either completely succeed or completely fail. The business requires strong consistency, ACID transactions, point-in-time recovery, availability across more than one Availability Zone, and seven years of transaction history. Read traffic is significantly higher than write traffic.
Build from scratchMultiple choiceFill the gaps - Real-time applicationsprofessional
Real-Time Collaborative Whiteboard
A company is building an online collaborative whiteboard where thousands of users can work on the same board at once. When one user moves an object, every other connected user must receive that change immediately. The platform needs persistent two-way connections, real-time updates, millions of connection events, automatic scaling, no server fleet to manage, and authentication before anyone joins a board. Board state has to be stored durably, while the collaboration state that is read and written constantly should be extremely fast.
Build from scratchMultiple choiceFill the gaps - Global deliveryassociate
Global E-Commerce Catalogue
An e-commerce company operates in India, Europe, North America and Australia. Its product catalogue changes relatively infrequently, but millions of users browse products every hour. The company wants low latency globally, protection against traffic spikes, high availability, pricing that varies by user and location, personalised recommendations, and as little load on the database as possible. Product images and static assets should not need to travel back to the origin on every request. The application already runs as containerised services.
+1Build from scratchMultiple choiceFill the gaps - Media processingassociate
Educational Video Platform
A startup launches a platform where users upload educational videos. A single uploaded video may need to be converted into 1080p, 720p, 480p and mobile-optimised formats. Encoding is CPU-intensive and can take several minutes, and thousands of videos may be uploaded at the same time. The company does not want to maintain dedicated encoding servers. A failed encoding job should be retried automatically, and one failed video must not block the others. Once processed, users should be able to stream the videos globally.
Build from scratchMultiple choiceFill the gaps - Streaming and IoTprofessional
Refrigerated Fleet Telemetry
A logistics company operates 3 million refrigerated trucks, and each truck sends temperature and GPS information every 10 seconds. The platform must receive millions of messages, cope with devices connecting and disconnecting constantly, process telemetry in near real time, raise an alert whenever a temperature crosses a threshold, keep the history for analytics, and drive a dashboard showing the current status of every truck. The fleet is expected to reach 10 million devices, and the company does not want to operate persistent servers responsible for maintaining device connections.
+1Build from scratchMultiple choiceFill the gaps - Real-time applicationsassociate
Live Collectibles Auction Platform
An online auction house runs live bidding events for collectible items. During an event each bidder's browser must hold an open two-way connection so that price changes are pushed out to every participant the moment they happen, without any client polling. The team wants nothing to size or patch, per-request billing, and a handler that runs only for the length of each message while scaling from dozens of participants to tens of thousands in seconds. Bidders sign in with an email address and password before joining, and every accepted bid is written to a durable relational store kept for seven years of regulatory audit. The current high bid and the ranking of bids per lot must be held in memory, updated with atomic counters and sorted structures, and published to subscribed handlers.
Build from scratchMultiple choiceFill the gaps - Decoupling and scaleassociate
Flash Sale Order Intake
A retailer runs a two-hour flash sale that drives roughly forty times normal checkout traffic. The fulfilment database behind checkout is relational and can absorb only a steady, modest rate of writes; it must never be the reason a customer's order is rejected, so the checkout endpoint has to accept an order and return success even while fulfilment is behind. Orders must survive a fulfilment outage without being lost, and the orders belonging to one customer must be processed in the sequence they were accepted. Once an order is committed, the customer is sent an email confirmation. Checkout is an ordinary HTTPS request from the storefront and the team does not want to run or scale servers for the spike.
Build from scratch - Orchestrationprofessional
Enterprise Order Workflow
A large enterprise runs an order-processing platform. An order moves through seven stages: created, validate customer, check inventory, reserve inventory, charge payment, create shipment, send confirmation. Each stage may involve a different microservice and some operations take minutes. If payment fails after inventory has been reserved, the system must release that inventory. If the shipment service is temporarily unavailable, the workflow should wait and retry rather than failing the whole order. The company wants visibility into the state of every order and does not want developers implementing complex workflow state management themselves.
Build from scratchMultiple choiceFill the gaps - Serverless webfoundational
Photo Sharing App, Global Launch
A two-person team is launching a photo sharing app worldwide next month. The front end is a static single-page application; there is no server-rendered HTML. Photos are uploaded by signed-in users, stored as original files, and served to viewers in Tokyo, London and São Paulo with as little latency as possible. Photo metadata — owner, caption, timestamp, tag list — is only ever read by a single key lookup or a query on the owner, never joined across tables, and read volume is expected to be a hundred times write volume. Users sign up with an email address and password. The team has no operations engineer and will not accept anything they have to patch or capacity-plan.
+1Build from scratchMultiple choiceFill the gaps - Event-driven processingassociate
Global RAW Image Processing
A photography company lets professional photographers upload RAW images ranging from 50 MB to 2 GB, from anywhere in the world. After upload several operations must occur: generate thumbnails, extract metadata, create preview images, run AI-based image classification, and store the original permanently. Processing may take several minutes and does not need to happen immediately. The company expects millions of uploads per month, and a marketing campaign could increase uploads twentyfold for a few hours. The upload path must remain available even when the processing workers are completely overwhelmed.
Build from scratchMultiple choiceFill the gaps - Resilience and DRprofessional
Disaster Recovery for a Critical SaaS
A SaaS company runs its production application in a single AWS Region. The system holds customer accounts, orders, payments, application configuration and uploaded documents. If that Region fails completely the business can tolerate roughly 15 minutes of data loss and 30 minutes of downtime. The company wants a disaster-recovery approach that is significantly cheaper than running a full duplicate production environment. Backups must be automated, encrypted and regularly tested, and the architecture should let the company bring the application up in another Region when it needs to.
+1Build from scratchMultiple choiceFill the gaps - Concurrency at scaleprofessional
Flash-Sale Ticket Booking
A concert-ticket platform releases 50,000 tickets at exactly 10:00 AM. Within seconds, hundreds of thousands of users attempt to purchase tickets simultaneously. The application must prevent two customers from purchasing the same seat. Checkout can take several seconds because payment authorization is performed by an external provider, and the company does not want to maintain a fleet of always-running application servers. If payment succeeds the reservation is confirmed; if payment fails or the customer abandons checkout, the seat should automatically become available again after 10 minutes. The architecture has to absorb sudden traffic spikes, prevent duplicate reservations, and avoid keeping a database connection open for every waiting customer.
Build from scratchMultiple choiceFill the gaps
Learn the shapes
16 architectures most scenarios turn out to be a variation of, each with the signals in a brief that point at it and what it costs you. They also appear on a blank canvas while you are building.
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Written reviews are on, via Experiential Labs.
Scoring is deterministic and runs with no API key at all — the AI only writes the commentary, and never touches the number.