Building Real-Time Collaborative Apps with CRDTs and Y.js

Building Real-Time Collaborative Apps with CRDTs and Y.js Real-time collaboration has become table stakes for modern applications. Users expect to see each other's cursors, watch edits appear instantly, and never lose work to a merge conflict. Figma, Notion, Google Docs, and Linear all deliver this experience seamlessly. The technology powering most of these applications? CRDTs — Conflict-free Replicated Data Types. If you've ever tried building collaborative features with naive approaches like last-write-wins or operational transformation (OT), you know the pain. Race conditions, lost updates, and complex server-side logic make it a nightmare. CRDTs eliminate an entire class of these problems by making conflicts mathematically impossible. In this article, we'll go from zero to a working collaborative application. You'll learn what CRDTs are, how Y.js implements them for JavaScript, and how to build both a collaborative text editor and a shared whiteboard with real code. We'll also cov