• Define Actors/Stakeholders:
  • Customers: anyone interested in purchasing their products.
  • Merchants/Providers
  • Third party systems (sources of truth).
• Define limitations and trade-offs:
  • Design decisions (weaknesses & strengths).
  • Number of write/read Transactions per day/month.
• Create a high level system design:
  • Constraints and Assumptions.
  • Limitations & Unknowns.
  • Out of scope.
  • Define Non-functional and functional requirements.
  • Define Risks and Strategies (Bottlenecks, Restrictions, delimit edges, Troubleshooting scenarios)
  • Define Deployment Strategy: Treat configuration as code (Ansible, Terraform, Jenkins, Docker and Kubernetes) and Deploy services independently.
  • Scaling to enforce high cohesion and loose coupling (Redundancy / Consistency).
  • Availability patterns: Fail-over (load balancer, managing traffic and DNS using public IPs or CNAME records), Database Replication (Master-slave, master-master), Federation, Sharding, etc
  • Consider the type of data: Put transactional data into SQL, put JSON documents into a document database, put telemetry data into a time series data base, put application logs in Elasticsearch and put blobs in Azure Blob Storage.
  • Performance: use asynchronous messaging with a pub/sub architecture (Kibana) and backend services using RPC-style messaging protocol.
  • Monitoring: use distributed tracing (NewRelic, Splunk) to identify the cause of the failure (Traces should include a correlation ID).

• Define Objective/Requeriments
  • Create a Search textbox for products
• Define Limitations
  • Ranking system
  • Number of products (database)
  • Number of categories (database)
  • Number of write Transactions per month
  • Number or read Transactions per month
• Out of Scope
  • Suggestions
  • Infinite scrolling
• Actions/Actors
  • Users (JWT roles)

Design WhatsApp-Scale Messaging — Core Design

Design the backend for a WhatsApp-like messaging system.

Data model: how do you store messages, conversations, users? Delivery: how does message delivery work end-to-end (sender → server → recipient)? Offline: how do you handle online vs offline recipients?

Design WhatsApp-Scale Messaging — Scale It

You now have 1B users, 100B messages/day (~1.15M msg/sec peak).

Bottlenecks: where does your Round 1 design break first? Fan-out: how do you handle group chats with 1,000 members?

Design WhatsApp-Scale Messaging — Hard Problems

Pick one to go deep on:

• Exactly-once delivery guarantees
• Message ordering across devices (multi-device sync)
• End-to-end encryption key distribution at scale

• Design a system that allow people to report fake accounts on Facebook

• Are there any details I need?
• Are there any restrictions?
• What are all the major parts?
• Then, refine as much as possible.

• The System Design Primer
• Ten design principles for Azure applications
• Evaluating Software Architectures for Real-Time Systems
• Architect's Guide to Frontend Frameworks
• BrowserDiet - How to lose weight in the browser
• System design: Como empezar el diseño de un sistema
• AWS Whitepapers & Guides - AWS technical content authored by AWS and the AWS community (technical guides and reference architecture diagrams).
• Browse Azure Architectures - Architecture diagrams and technology descriptions for reference architectures, real world examples of cloud architectures.
• Azure Cloud Design Patterns - useful design patterns for building reliable, scalable, secure applications in the cloud.