A new interactive tutorial demystifies CRDTs (Conflict-free Replicated Data Types) for developers building collaborative applications. The series starts with the basics of what CRDTs are - data structures that can be stored on different computers and sync without central servers. Each peer can update its own state instantly, with the guarantee that all peers will eventually converge on the same agreed-upon state.

This makes CRDTs perfect for applications like Google Docs and Figma that need real-time collaboration. The tutorial focuses on state-based CRDTs, which transmit their full state between peers and merge states together. While operation-based CRDTs only send user actions, they require strict message delivery guarantees that state-based CRDTs avoid. The author walks through implementing a Last Write Wins Register (LWW Register), a simple CRDT that overwrites its value with the most recent timestamp.

The tutorial includes an interactive playground where you can experiment with LWW Registers - turning network connections on and off, adjusting latency, and seeing how timestamps and peer IDs determine which value wins. The code implementation shows how the merge function ensures commutativity, associativity, and idempotence - the three mathematical properties that guarantee all peers arrive at the same result. By the end, developers will understand how to build collaborative pixel art editors and other real-time applications without relying on a central server.