Design a Real-Time Permissions and Sharing System
Last updated: April 5, 2025
Quick Overview
Design a permissions system for Canva that handles design sharing, team access control, folder hierarchies, and real-time permission propagation at scale.
Canva
April 5, 202510
5
2,678 solved
Design a permissions system for Canva that handles design sharing, team access control, folder hierarchies, and real-time permission propagation at scale.
As Canva grows into enterprise markets with Canva Teams, permission management becomes increasingly complex. The system must handle individual sharing, team-based access, folder hierarchies with inheritance, public/private visibility, and real-time permission changes that immediately affect active editing sessions.
What the Interviewer Expects
- Design an access control model supporting user, team, and organization-level permissions
- Handle permission inheritance through folder hierarchies efficiently
- Ensure permission changes propagate to active editing sessions in real time
- Design for both simplicity (individual users) and complexity (enterprise teams)
- Discuss permission checking performance at high QPS
Key Topics to Cover
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- How would you handle a team admin revoking edit access for a user who is currently editing a design?
- How would you implement shareable links with different permission levels?
- How would you audit who accessed what and when for enterprise compliance?
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Practice System Design ProblemsSample Answer
Access Control Model
Use a relationship-based access control (ReBAC) model inspired by Google Zanzibar. Permissions are expressed as relationships: (user:alice, editor, de...
Inheritance and Performance
Folder permission inheritance uses a materialized path approach. Each resource stores its ancestor chain (e.g., /org:canva/folder:marketing/folder:q3-...
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