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System Design Kit

A system design method plus ten reference designs: chat, news feed, payment ledger, rate limiter, search, notifications, video, scheduling, rides, editing.

Step 1

Method and patterns

  1. System Design Document Template

    Full

    System design at scale – requirements, capacity estimates (KaTeX), API, data model, HLD, deep dives, reliability, cost, trade-offs

  2. Database Design Document Template (ERD and Physical Model)

    Full

    Database design: DBMS choice, conceptual, logical and physical models, indexes, partitioning, integrity, security, backup, capacity

  3. Multi-Tenancy Design Template (SaaS)

    Full

    SaaS tenancy model (silo, pool, bridge), tenant context, data isolation, noisy neighbours, lifecycle, residency, cost per tenant

  4. Event Sourcing and CQRS Design Template

    Standard

    Event-sourced service design: fit check, event catalogue, versioning and upcasting, store, projections, idempotency, crypto-shredding

  5. Microservice Specification Template (Service Canvas)

    Standard

    Service canvas: bounded context, owner, APIs and events, data owned, dependencies, SLOs, scaling, config, deploy, observability

  6. Frontend Architecture Document Template

    Full

    Web frontend architecture: rendering per route, state, data caching, design system, Core Web Vitals budgets, a11y, i18n, CSP, RUM

    Core Web Vitals (web.dev); WCAG 2.2 AA

  7. Mobile App Architecture Template

    Standard

    Mobile app architecture: native vs cross-platform, MVVM/Clean layers, offline sync, secure storage, auth, privacy, releases, testing

Step 2

Reference designs

  1. Chat System Design Template (Reference Design)

    Full

    Real-time 1:1 and group chat: WebSocket gateways, per-conversation ordering, fan-out, receipts, offline sync, push, E2EE

  2. News Feed System Design Template (Reference Design)

    Full

    Social feed: hybrid fan-out on write and read, celebrity threshold, ranking pipeline, feed cache, snapshot pagination, media

  3. Payment Ledger System Design Template (Reference Design)

    Full

    Payments and double-entry ledger: idempotency keys, payment state machine, PSPs, outbox, reconciliation, audit, PCI DSS scope

  4. Rate Limiter System Design Template (Reference Design)

    Full

    Distributed rate limiter: token bucket vs window algorithms, atomic Redis scripts, multi-region shares, 429 headers, fail-open

  5. Search Autocomplete System Design Template (Reference Design)

    Full

    Typeahead: trie/FST/edge n-gram index, popularity and recency ranking, query-log pipeline, edge cache, latency budget, safety

  6. Notification Service System Design Template (Reference Design)

    Full

    Push, email, SMS and in-app: templates, preferences and opt-out, priority queues, caps, provider failover, retries, dedup

  7. Video Streaming System Design Template (Reference Design)

    Full

    Video upload and ABR streaming: chunked transcoding, renditions ladder, CMAF HLS/DASH, CDN, DRM note, view counts, storage tiers

  8. Job Scheduler System Design Template (Reference Design)

    Full

    Distributed scheduler: cron, delayed and one-off jobs, leases and visibility timeouts, fencing, idempotent handlers, retries, DLQ

  9. Ride-Hailing Dispatch System Design Template (Reference Design)

    Full

    Ride matching: location ingestion, H3/geohash index, batched matching, ETA, trip state machine, single assignment, surge note

  10. Collaborative Editing System Design Template (Reference Design)

    Full

    Real-time co-editing: OT vs CRDT, sequence CRDT, state-vector sync, presence, offline merge, snapshots and compaction, access