System design templates
Every template is a real, editable diagram with a short explanation of the design, its trade-offs and where it breaks. Open one and ArchBoard builds it as a new scene on your device. Nothing is uploaded and there is no account.
Interview classics
URL Shortener
A read-heavy link shortener with a CDN, cache and key generator in front of a database.
Pastebin Service
Store and share text snippets with object storage for content and a database for metadata.
Rate Limiter
A distributed rate limiter at the gateway with shared counters and a rules store.
Notification System
Fan out email, SMS and push notifications through a queue with per-channel workers.
Chat Application
Real-time chat with WebSocket gateways, a message store, presence and offline push.
News Feed
Fan-out on write for most users and fan-out on read for celebrities, behind a feed cache.
Ride Sharing
Match riders and drivers with a location service, geospatial index and trip state machine.
Video Streaming
Upload, transcode into adaptive bitrate renditions and serve video segments through a global CDN.
File Storage and Sync
Chunked file sync with a metadata service, block store and change notifications.
Web Crawler
A polite distributed crawler with a URL frontier, fetchers, parsers and dedup storage.
Search Autocomplete
Type-ahead suggestions served from an in-memory trie rebuilt from query logs.
Distributed Key-Value Store
A Dynamo-style store with consistent hashing, replication and quorum reads and writes.
Ticket Booking
Prevent double booking with seat holds, a waiting room and transactional payments.
Payment System
A payment flow with idempotent APIs, a ledger, a provider gateway and reconciliation.
Distributed Cache
A sharded cache tier with consistent hashing, replicas and a cache-aside application.
Unique ID Generator
Time-ordered 64-bit identifiers from many generators without central coordination.
Metrics and Monitoring
Collect, store, query and alert on time-series metrics from a fleet of services.
E-commerce Checkout
Cart, inventory reservation, payment and order events across cooperating services.
Web architecture
Three-Tier Web Application
The classic presentation, application and data tiers behind a load balancer.
Microservices with API Gateway
An API gateway in front of independently deployable services that each own their data.
Serverless API
An HTTP API backed by stateless functions, a managed database and an event queue for slow work.
Jamstack Site
Pre-built static pages on a CDN with serverless functions for the dynamic parts.
Backend for Frontend
One tailored backend per client type, each aggregating the same downstream services for its screens.
Strangler Fig Migration
Incrementally replace a legacy monolith by routing slices of traffic to new services.
Multi-Tenant SaaS
Shared application tier with tenant routing, isolation and per-tenant limits.
Data and storage
Read Replicas
Scale reads with asynchronous replicas while the primary handles all writes.
Database Sharding
Partition data across several databases with a routing layer, a shard map and a rebalancing job.
CQRS
Separate write and read models, kept in sync by events, for independent scaling.
Data Lake and ETL
Land raw data in object storage, transform on a schedule and load a warehouse.
Cache-Aside Pattern
The application checks the cache first and loads from the database on a miss.
Write-Through Cache
Writes go through the cache, either synchronously to the database or batched behind it.
Change Data Capture
Stream database changes from the transaction log to search, cache and analytics.
Messaging and events
Pub/Sub Fan-Out
One publisher, one topic and many independent subscribers, each consuming at its own pace.
Event Sourcing
Store every change as an immutable event and derive current state by replay.
Saga Orchestration
A coordinator drives a multi-service workflow with compensating actions on failure.
Transactional Outbox
Write business data and an event in one transaction, then relay the event reliably.
Dead Letter Queue
Isolate poison messages with retries, a dead letter queue and an operator replay path.
Reliability
Multi-Region Active-Passive
A warm standby region with replicated data and DNS failover for disaster recovery.
Blue-Green Deployment
Two identical environments with an instant traffic switch and a quick rollback.
Circuit Breaker
Stop calling a failing dependency, serve a fallback response and probe carefully for recovery.
CDN with Origin Shield
Edge caches, a shield layer and an origin protected from simultaneous cache-miss storms.
Security
DevOps
CI/CD Pipeline
Build, test, scan and deploy containers from a pull request all the way to Kubernetes.
Observability Stack
Metrics, logs and traces collected from services into dashboards and alerts.
Kubernetes Cluster with Ingress
Ingress, services, pods, config and persistent storage inside a Kubernetes cluster.
Feature Flag Rollout
Decouple deploy from release with flags, percentage rollouts and a kill switch.