Design Anonymous Group Messaging

1. Problem Statement

2. Architecture Discussion Map

Use this as one discussion aid, not a single correct answer. Your design should follow from the requirements, scale, and trade-offs you establish.

graph LR
    A["Design Anonymous Group Messaging"]
    A --> F1["Group-scoped pseudonym generation"]
    A --> F2["Authorization and identity mapping"]
    A --> F3["Real-time and offline message delivery"]
    A --> F4["Media attachments and fan-out"]
    A --> F5["Moderation, reporting, and privacy"]

3. Key Focus Areas

• 1
  Group-scoped pseudonym generation
• 2
  Authorization and identity mapping
• 3
  Real-time and offline message delivery
• 4
  Media attachments and fan-out
• 5
  Moderation, reporting, and privacy

4. What the Interviewer Looks For

The interviewer probes these areas, and the report grades the interview against them.

• Threat model, scope, and estimation
• Pseudonymous identity design
• Messaging, ordering, and delivery
• Moderation, abuse, and legal access
• Privacy leakage and data protection

5. What Strong Candidates Should Demonstrate

• Separate durable account identity from group-scoped pseudonyms.
• Preserve moderation and abuse investigation without exposing identities to members.
• Design reliable real-time and offline message delivery.