Introduction

This post provides a comprehensive list of common system design interview questions for Meta’s Senior Software Engineer positions. These questions are based on extensive research, interview experiences, and Meta’s actual products and systems.

Note: For detailed preparation strategies, see the Meta System Design Interview Guide.

Meta System Design Interview Overview

Interview Format

  • Duration: 45 minutes
  • Format: Known as the “Pirate Interview” round
  • Focus: Design skills demonstration - open-ended questions
  • Process: Discussion and whiteboarding/virtual board
  • Evaluation: Problem-solving approach, technical depth, communication

Evaluation Criteria

Meta evaluates candidates on four key areas:

  1. Problem Navigation: Organize problem space, identify constraints, ask clarifying questions
  2. Solution Design: Design working solutions, consider the big picture
  3. Technical Excellence: Dive into technical details, identify dependencies and trade-offs
  4. Technical Communication: Articulate vision clearly, address feedback

Common Meta System Design Questions

Meta-Specific Product Questions (Highest Priority)

These questions are directly related to Meta’s products and are asked most frequently.

1. Design Facebook News Feed

Key Features:

  • Users see news feed containing posts from friends and followed pages
  • Users can post and like statuses (text, images, videos)
  • Users can send friend requests and follow pages
  • Real-time feed updates

Challenges:

  • Real-time feed generation
  • Ranking algorithms for feed relevance
  • Handling billions of users and posts
  • Efficient data retrieval and caching
  • Personalization and relevance

Key Components:

  • Feed generation service
  • Ranking service
  • Content delivery network (CDN)
  • Caching layer
  • Graph database for social connections

Key Features:

  • Search posts, statuses, videos from friends and followed pages
  • Text-based search (extendable to multimedia)
  • Real-time search updates

Challenges:

  • Indexing massive amounts of content
  • Real-time search updates
  • Ranking and relevance algorithms
  • Scalability for millions of queries per second
  • Privacy and access control

Key Components:

  • Search index (Elasticsearch, custom)
  • Indexing pipeline
  • Query processing
  • Ranking service
  • Access control layer

3. Design Facebook Messenger / WhatsApp

Key Features:

  • 1:1 conversations between users
  • Track online/offline status
  • Group conversations
  • Push notifications
  • Message delivery confirmation

Challenges:

  • Real-time message delivery
  • Message persistence and ordering
  • Presence/status management
  • Handling millions of concurrent connections
  • End-to-end encryption
  • Message synchronization across devices

Key Components:

  • Message delivery service
  • Presence service
  • Notification service
  • Message storage
  • WebSocket/connection management

4. Design Instagram

Key Features:

  • Upload and share photos/videos
  • Follow other users
  • Like photos
  • Scrollable feed of photos from followed users
  • Stories feature

Challenges:

  • Media storage and CDN distribution
  • Feed generation and ranking
  • Image processing and optimization
  • Real-time updates for likes and comments
  • High-volume media uploads

Key Components:

  • Media upload service
  • Image processing pipeline
  • CDN for media delivery
  • Feed generation service
  • Activity tracking

5. Design Live Commenting

Key Features:

  • Real-time comment feed for posts
  • Users see new comments as they appear
  • Handle concurrent comments from multiple users
  • Comment threading

Challenges:

  • Real-time data synchronization
  • WebSocket or polling mechanisms
  • Handling high concurrency
  • Maintaining comment order and consistency
  • Scalability for viral posts

Key Components:

  • Real-time notification service
  • Comment storage
  • WebSocket connection management
  • Message queue for comment processing

General System Design Questions (High Priority)

These are common system design patterns that appear frequently in Meta interviews.

6. Design a Distributed Cache System

Key Features:

  • High-performance caching
  • Distributed across multiple nodes
  • Cache eviction strategies
  • Consistency models

Challenges:

  • Cache coherence
  • Distributed caching
  • Eviction policies
  • Cache invalidation
  • Network partitioning

7. Design a URL Shortener (TinyURL)

Key Features:

  • Shorten long URLs
  • Redirect to original URLs
  • Analytics and tracking
  • Custom short URLs

Challenges:

  • Generating unique short codes
  • High read/write ratio
  • Scalability
  • Redirect performance
  • Analytics at scale

8. Design a Distributed Lock Service

Key Features:

  • Distributed locking mechanism
  • Lease-based locking
  • Automatic lock expiration
  • High availability

Challenges:

  • Consensus algorithms
  • Lock expiration and renewal
  • Deadlock prevention
  • Network partitions
  • Performance at scale

9. Design a Rate Limiter

Key Features:

  • Limit requests per user/IP
  • Multiple rate limiting strategies
  • Distributed rate limiting
  • High-throughput support

Challenges:

  • Sliding window algorithms
  • Distributed coordination
  • Token bucket implementation
  • Performance optimization
  • Accurate rate limiting

10. Design a Distributed Counter

Key Features:

  • Count events across distributed systems
  • Real-time counting
  • High write throughput
  • Eventual consistency

Challenges:

  • Distributed counting
  • Consistency vs. performance
  • Handling high write rates
  • Aggregation strategies
  • Sharding and partitioning

Real-Time and Event-Driven Systems (High Priority)

11. Design a Real-Time Analytics System

Key Features:

  • Real-time event processing
  • Aggregations and metrics
  • Dashboard updates
  • High-throughput event ingestion

Challenges:

  • Stream processing
  • Low-latency aggregations
  • Handling high event rates
  • Data retention
  • Query performance

12. Design a Notification System

Key Features:

  • Multi-channel notifications (push, email, SMS)
  • Notification preferences
  • Delivery tracking
  • High-throughput delivery

Challenges:

  • Multi-channel delivery
  • Notification batching
  • Delivery reliability
  • User preferences
  • Rate limiting per channel

13. Design a Real-Time Collaboration System

Key Features:

  • Real-time document editing
  • Conflict resolution
  • Presence awareness
  • Change synchronization

Challenges:

  • Operational transforms
  • Conflict resolution
  • Real-time synchronization
  • Consistency models
  • Scalability

Data-Intensive Systems (Medium Priority)

14. Design Proximity Server

Key Features:

  • Add, update, and delete places
  • Query nearby places within distance
  • Query events near a place at specific time
  • Geospatial queries

Challenges:

  • Geospatial indexing (GeoHash, R-trees)
  • Efficient proximity queries
  • Handling time-based queries
  • Scalability for location services
  • Real-time updates

Key Components:

  • Geospatial database
  • Location indexing service
  • Query processing
  • Caching layer

15. Design Typeahead Suggestions (Autocomplete)

Key Features:

  • Suggest top 10 search queries based on typed characters
  • Popularity determined by search frequency
  • Real-time suggestions
  • Low-latency responses

Challenges:

  • Real-time suggestions
  • Efficient prefix matching (Trie)
  • Ranking and relevance
  • Handling millions of queries
  • Response time optimization

Key Components:

  • Trie data structure
  • Ranking service
  • Caching layer
  • Query processing

16. Design Top N Songs / Trending Topics

Key Features:

  • Get top N songs based on listen frequency
  • Time-based windowing (past X days)
  • Ranking by popularity
  • Real-time updates

Challenges:

  • Real-time aggregation
  • Efficient top-K algorithms
  • Sliding window calculations
  • Handling high-volume data streams
  • Ranking accuracy

17. Design a Web Crawler

Key Features:

  • Download web pages from seed URLs
  • Index pages for future retrieval
  • Handle duplicate URLs
  • Crawl all connected pages

Challenges:

  • URL deduplication
  • Respecting robots.txt
  • Rate limiting
  • Distributed crawling
  • Handling different content types
  • Politeness and fairness

18. Design a Distributed File System

Key Features:

  • File storage and retrieval
  • Replication and fault tolerance
  • High availability
  • Scalability

Challenges:

  • Distributed storage
  • Consistency models
  • Replication strategies
  • Fault tolerance
  • Performance optimization

Specialized Systems (Medium Priority)

19. Design Privacy Settings

Key Features:

  • Specify privacy levels for posts (Public, Friends, etc.)
  • Control post visibility to specific user sets
  • Friends of friends, custom groups
  • Efficient privacy checks

Challenges:

  • Efficient privacy checks
  • Access control enforcement
  • Querying posts with privacy constraints
  • Scalability for billions of posts
  • Complex privacy rules

20. Design a Distributed Task Scheduler

Key Features:

  • Schedule and execute tasks
  • Task priorities and dependencies
  • Fault tolerance
  • Scalability

Challenges:

  • Task scheduling algorithms
  • Dependency management
  • Fault tolerance
  • Resource allocation
  • Load balancing

21. Design a Distributed Logging System

Key Features:

  • Collect logs from distributed services
  • Log aggregation and storage
  • Log search and querying
  • Real-time log streaming

Challenges:

  • High-volume log ingestion
  • Log storage and retention
  • Search performance
  • Real-time streaming
  • Cost optimization

22. Design a Distributed Configuration System

Key Features:

  • System-wide configuration
  • Dynamic configuration updates
  • Configuration versioning
  • Rollback mechanisms

Challenges:

  • Configuration distribution
  • Consistency across services
  • Version management
  • Rollback strategies
  • Performance impact

Infrastructure and Scalability Questions (Lower Priority)

23. Design a Load Balancer

Key Features:

  • Distribute requests across servers
  • Health checking
  • Multiple routing algorithms
  • High availability

Challenges:

  • Load balancing algorithms
  • Health checking
  • Session affinity
  • High availability
  • Performance optimization

24. Design a Distributed Database

Key Features:

  • Distributed data storage
  • Replication and consistency
  • Query processing
  • Transaction support

Challenges:

  • CAP theorem trade-offs
  • Replication strategies
  • Consistency models
  • Partitioning and sharding
  • Query routing

25. Design a Content Delivery Network (CDN)

Key Features:

  • Global content distribution
  • Edge caching
  • Origin server management
  • Cache invalidation

Challenges:

  • Edge server placement
  • Cache strategies
  • Invalidation mechanisms
  • Latency optimization
  • Cost optimization

Question Categories by Frequency

Tier 1: Most Common Questions (Must Practice)

These questions appear in 70%+ of Meta interviews:

  1. Design Facebook News Feed (#1)
  2. Design Facebook Messenger / WhatsApp (#3)
  3. Design Instagram (#4)
  4. Design Facebook Status Search (#2)
  5. Design Live Commenting (#5)

Tier 2: Very Common Questions (High Priority)

These questions appear in 40-70% of interviews:

  1. Design a Distributed Cache System (#6)
  2. Design a URL Shortener (#7)
  3. Design a Rate Limiter (#9)
  4. Design a Real-Time Analytics System (#11)
  5. Design Proximity Server (#14)
  6. Design Typeahead Suggestions (#15)

Tier 3: Common Questions (Medium Priority)

These questions appear in 20-40% of interviews:

  1. Design a Distributed Lock Service (#8)
  2. Design a Notification System (#12)
  3. Design Top N Songs / Trending Topics (#16)
  4. Design a Web Crawler (#17)
  5. Design Privacy Settings (#19)
  6. Design a Distributed Task Scheduler (#20)

Tier 4: Less Common Questions (Lower Priority)

These questions appear in 10-20% of interviews:

  1. Design a Distributed Counter (#10)
  2. Design a Real-Time Collaboration System (#13)
  3. Design a Distributed File System (#18)
  4. Design a Distributed Logging System (#21)
  5. Design a Distributed Configuration System (#22)
  6. Design a Load Balancer (#23)
  7. Design a Distributed Database (#24)
  8. Design a Content Delivery Network (#25)

Meta-Specific Question Patterns

Pattern 1: Social Graph Problems

  • News Feed
  • Friend Suggestions
  • Social Search
  • Privacy Settings

Key Concepts:

  • Graph databases
  • Social graph algorithms
  • Privacy and access control
  • Feed ranking

Pattern 2: Real-Time Systems

  • Live Commenting
  • Messenger/Chat
  • Real-Time Analytics
  • Notification Systems

Key Concepts:

  • WebSockets
  • Pub/Sub systems
  • Message queues
  • Event streaming

Pattern 3: Content Systems

  • Instagram
  • Media Storage
  • CDN Design
  • Content Delivery

Key Concepts:

  • Media processing
  • CDN architecture
  • Storage systems
  • Image/video optimization

Pattern 4: Search and Discovery

  • Status Search
  • Typeahead/Autocomplete
  • Proximity Server
  • Trending Topics

Key Concepts:

  • Search indexing
  • Trie data structures
  • Geospatial indexing
  • Ranking algorithms

How to Use This List

Preparation Strategy

  1. Start with Tier 1 Questions
    • Master the most common Meta-specific questions
    • Understand Meta’s products deeply
    • Practice with detailed solutions
  2. Practice Tier 2 Questions
    • Cover common system design patterns
    • Understand distributed systems concepts
    • Practice problem exploration
  3. Review Tier 3 & 4 Questions
    • Familiarize with concepts
    • Understand basic approaches
    • Know when to apply them

Practice Approach

For each question, practice:

  1. Problem Navigation
    • Ask clarifying questions
    • Gather requirements
    • Understand constraints and scale
  2. Solution Design
    • High-level architecture
    • Component design
    • Data flow and interactions
  3. Technical Excellence
    • Detailed component design
    • Technology choices
    • Scalability considerations
    • Trade-offs analysis
  4. Technical Communication
    • Clear explanations
    • Diagrams and visualizations
    • Address feedback
    • Discuss alternatives

Interview Tips

  1. Ask Questions First
    • Clarify requirements
    • Understand scale
    • Identify constraints
    • Understand use cases
  2. Think at Scale
    • Meta operates at massive scale
    • Think billions of users
    • Consider global distribution
    • Plan for high throughput
  3. Discuss Trade-offs
    • Performance vs. consistency
    • Latency vs. throughput
    • Cost vs. reliability
    • Simplicity vs. flexibility
  4. Show Depth
    • Dive into technical details
    • Discuss implementation challenges
    • Consider edge cases
    • Address failure scenarios
  5. Communicate Clearly
    • Explain your thought process
    • Use diagrams effectively
    • Listen to feedback
    • Adjust approach when needed

Key Concepts to Master

Distributed Systems

  • Consistency Models: Strong, eventual, causal
  • CAP Theorem: Consistency, Availability, Partition tolerance
  • Replication: Master-slave, multi-master, quorum
  • Sharding: Horizontal partitioning strategies
  • Load Balancing: Algorithms and strategies

Scalability Patterns

  • Caching: Multi-level caching, cache strategies
  • CDN: Content delivery, edge caching
  • Database Scaling: Read replicas, sharding, partitioning
  • Message Queues: Async processing, event streaming
  • Microservices: Service decomposition, communication

Real-Time Systems

  • WebSockets: Persistent connections, real-time updates
  • Pub/Sub: Event-driven architectures
  • Stream Processing: Real-time data processing
  • WebRTC: Peer-to-peer communication

Data Systems

  • Storage: SQL, NoSQL, object storage
  • Indexing: Search indexes, geospatial indexes
  • Aggregation: Real-time aggregations, batch processing
  • Analytics: OLAP, OLTP, data warehousing

Meta-Specific Considerations

Scale Expectations

  • Users: Billions of users
  • Requests: Millions of QPS
  • Data: Petabytes of data
  • Global: Worldwide distribution
  • Real-time: Low-latency requirements

Technology Stack Awareness

Meta commonly uses:

  • Languages: Python, C++, Java, Hack (PHP)
  • Databases: MySQL, RocksDB, TAO
  • Messaging: Thrift, Protocol Buffers
  • Caching: Memcached, Redis
  • Storage: Haystack (photo storage), HDFS

Product Awareness

  • Understand Facebook, Instagram, WhatsApp, Messenger
  • Know Meta’s infrastructure (TAO, RocksDB, etc.)
  • Understand Meta’s engineering culture
  • Be aware of Meta’s open-source projects

What Interviewers Look For

Meta-Specific Product Knowledge

  1. Product Understanding
    • Deep understanding of Meta products
    • Can discuss product features
    • Red Flags: No product knowledge, vague understanding, wrong features
  2. Scale Thinking
    • Thinks at Meta scale (billions)
    • Understands global distribution
    • Red Flags: Small scale thinking, no global awareness, wrong scale
  3. Meta-Specific Patterns
    • Understands Meta’s patterns
    • Can apply Meta approaches
    • Red Flags: Generic solutions, no Meta patterns, wrong approach

System Design Skills

  1. Distributed Systems Expertise
    • Scalability patterns
    • Consistency models
    • Reliability design
    • Red Flags: No scalability, wrong consistency, no reliability
  2. Problem-Solving Approach
    • Structured approach
    • Asks clarifying questions
    • Red Flags: Unstructured, no questions, jumps to solution
  3. Technical Depth
    • Dives into details
    • Discusses trade-offs
    • Red Flags: Surface level, no details, no trade-offs

Communication Skills

  1. Clear Articulation
    • Explains clearly
    • Uses diagrams effectively
    • Red Flags: Unclear, poor diagrams, confusing
  2. Thought Process
    • Shows reasoning
    • Explains decisions
    • Red Flags: No reasoning, no decisions, unclear
  3. Trade-off Discussion
    • Discusses alternatives
    • Justifies choices
    • Red Flags: No alternatives, no justification, dogmatic

Meta-Specific Focus

  1. Meta Product Expertise
    • Deep Meta product knowledge
    • Scale understanding
    • Key: Demonstrate Meta product expertise
  2. Distributed Systems Mastery
    • Strong distributed systems knowledge
    • Meta-scale thinking
    • Key: Show distributed systems mastery

Conclusion

This list provides a comprehensive overview of common Meta Senior Software Engineer system design interview questions. Remember:

  • Focus on Meta-specific questions first (News Feed, Messenger, Instagram)
  • Master distributed systems fundamentals (scalability, consistency, reliability)
  • Practice problem-solving approach, not memorizing solutions
  • Think at Meta scale (billions of users, global distribution)
  • Show your thought process, communicate clearly
  • Discuss trade-offs, make informed decisions

Key Success Factors:

  1. Deep understanding of Meta’s products
  2. Strong distributed systems knowledge
  3. Clear problem-solving approach
  4. Excellent communication skills
  5. Ability to think at massive scale

Good luck with your Meta Senior Software Engineer interview preparation!