Design a Collaborative Real-Time Canvas Editor
Last updated: April 5, 2025
Quick Overview
Design the backend infrastructure for a collaborative design editor where multiple users can simultaneously edit the same canvas with real-time conflict resolution.
Canva
April 5, 202514
8
2,341 solved
Design the backend infrastructure for a collaborative design editor where multiple users can simultaneously edit the same canvas with real-time conflict resolution.
This is a core system design question at Canva. The collaborative editor is the heart of Canva's product, serving 260M+ MAU who frequently co-edit designs in real time. The interviewer expects deep understanding of CRDTs or operational transforms, RSocket/WebSocket communication, and conflict resolution strategies at global scale.
What the Interviewer Expects
- Explain the trade-offs between CRDTs and operational transforms for conflict resolution
- Design a communication layer using RSocket or WebSockets for real-time updates
- Handle network partitions and offline editing with eventual consistency
- Propose a storage strategy for design documents with version history
- Discuss scaling to support millions of concurrent editing sessions globally
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 user going offline for hours and then reconnecting with many local edits?
- How would you implement undo/redo in a multi-user collaborative context?
- What happens when two users simultaneously move the same element to different positions?
- How would you optimize bandwidth for users on slow connections?
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Practice System Design ProblemsSample Answer
Requirements
Functional Requirements
- Real-time Collaboration: Multiple users can edit the same canvas simultaneously with changes reflected in real-time.
- Conflict Resolution: Implement conflict r...
Capacity Estimation
Given 260M+ MAU, let's break down the estimates:
- Concurrent Users: Assume 5% concurrent users at peak times, leading to 13M concurrent users.
- Editing Sessions: Each user may have a...
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