Simon Willison’s Weblog


6 items tagged “crdt”


Making CRDTs 98% more efficient (via) Outstanding piece of explanatory writing by Jake Lazaroff showing how he reduced the transmitted state of his pixel art CRDT implementation from 643KB to 15KB using a progression of tricks, each of which is meticulously explained and accompanied by an interactive demo. # 17th October 2023, 5:15 pm

An Interactive Intro to CRDTs (via) Superb interactive essay by Jake Lazaroff, providing a very clear explanation of how the fundamental mechanisms behind CRDTs (Conflict-free Replicated Data Types) work. The interactive explanatory demos are very neatly designed and a lot of fun to play with. # 4th October 2023, 3:10 pm


Building a BFT JSON CRDT (via) Jacky Zhao describes their project to build a CRDT library for JSON data in Rust, and includes a thorough explanation of what CRDTs are and how they work. “I write this blog post mostly as a note to my past self, distilling a lot of what I’ve learned since into a blog post I wish I had read before going in”—the best kind of blog post! # 21st November 2022, 7:56 pm


Notes on Apple’s Notes app keeps its data in a SQLite database at ~/Library/Group\ Containers/—but it’s pretty difficult to extract data from. It turns out the note text is stored as a gzipped protocol buffers object in the ZICNOTEDATA.ZDATA column. Steve Dunham did the hard work of figuring out how it all works—the complexity stems from Apple’s use of CRDT’s to support seamless multiple edits from different devices. # 9th December 2021, 10:39 pm


I was wrong. CRDTs are the future (via) Joseph Gentle has been working on collaborative editors since being a developer on Google Wave back in 2010, later building ShareJS. He’s used Operational Transforms throughout, due to their performance and memory benefits over CRDTs (Conflict-free replicated data types)—but the latest work in that space from Martin Kleppmann and other researchers has seen him finally switch allegiance to these newer algorithms. As a long-time fan of collaborative editing (ever since the Hydra/SubEthaEdit days) I thoroughly enjoyed this as an update on how things have evolved over the past decade. # 28th September 2020, 9:03 pm


The Xi Text Engine CRDT (via) Xi is “a modern editor with a backend written in Rust”—an open-source text editor project from Google built on some very interesting computer science (Conflict-free Replicated Data Types). It’s a native editor with server-backed synchronization as a first-class concept. # 13th October 2017, 10:32 pm