Awesome CRDT

A collection of awesome CRDT resources

Table of Contents

• Know Before You Go
  • Introduction
  • Set Theory
  • Order Theory
  • Clocks
• Academic Papers
  • Foundations
    • Clocks
  • Applications
    • Clocks
  • Proof and Verification
• Blogs
• Skepticism
• Videos
  • Playlists
• Implementations
  • Data Structures
    • Toy Implementations
  • Text Editors
  • Databases and Logs
  • Productivity
• More Lists

Know Before You Go

Introduction

• CRDT.tech: what a CRDT is, and why you would want one
• CRDT Glossary: the vocabulary the rest of this list assumes

Set Theory

• Set Notation and Concepts
• Set theory symbols

Order Theory

• Partially ordered set (Wikipedia)
• Total Order (Wikipedia)
• Causal Ordering
• Semilattice (Wikipedia)
• A CRDT Primer Part I: Defanging Order Theory (2015)

Clocks

• Logical Clock (Wikipedia)
• Lamport Timestamps (Wikipedia)
• Assigning Lamport & Vector Timestamps
• Vector Clock (Wikipedia)
• Version Vector (Wikipedia)
• Why Logical Clocks are Easy (2016)

Academic Papers

• CRDT Papers: the exhaustive, continuously updated bibliography

Foundations

• The Only Undoable CRDTs are Counters - Stephen Dolan (2020)
• Pure Operation-Based Replicated Data Types - Carlos Baquero et. al. (2017)
• Large-Scale Geo-Replicated Conflict-free Replicated Data Types - Carlos Bartolomeu (2015)
• A comprehensive study of Convergent and Commutative Replicated Data Types - Marc Shapiro et. al. (2011)
• Convergent and Commutative Replicated Data Types - Marc Shapiro et. al. (2011)
• Conflict-free Replicated Data Types - Marc Shapiro et. al. (2011)
• Evaluating CRDTs for Real-time Document Editing - Mehdi Ahmed-Nacer et. al. (2011)
• Consistency, Availability, and Convergence - Prince Mahajan et. al. (2011)
• CRDTs: Consistency without concurrency control - Mihai Letia et. al. (2009)
• Designing a commutative replicated data type - Marc Shapiro et. al. (2007)
• Achieving Convergence, Causality-Preservation, and Intention-Preservation in Real-Time Cooperative Editing Systems - Chengzheng Sun et. al. (1998)

Clocks

• Dotted Version Vectors: Efficient Causality Tracking for Distributed Key-Value Stores - Nuno Preguiça et. al. (2012)
• Virtual Time and Global States of Distributed Systems - Friedemann Mattern (1988)
• Timestamps in Message-Passing Systems That Preserve the Partial Ordering - Colin Fidge (1988)
• Time, Clocks, and the Ordering of Events in a Distributed System - Leslie Lamport (1978)

Applications

• Collaborative Text Editing with Eg-walker: Better, Faster, Smaller - Joseph Gentle & Martin Kleppmann (2024)
• RGASplit: High Responsiveness for Group Editing CRDTs - Loïck Briot et. al. (2016)
• Yjs: A Framework for Near Real-Time P2P Shared Editing on Arbitrary Data Types - Petru Nicolaescu et. al. (2015)
• SwiftCloud: Fault-Tolerant Geo-Replication Integrated all the Way to the Client Machine - Marek Zawirski et. al. (2013)
• LSEQ: an Adaptive Structure for Sequences in Distributed Collaborative Editing - Brice Nédelec et. al. (2013)
• RGA, RHT, RFA: Replicated abstract data types: Building blocks for collaborative applications - Hyun-Gul Roh (2011)
• WOOTR: Abstract unordered and ordered trees CRDT - Stéphane Martin et. al. (2011)
• COPS: Don't Settle for Eventual: Scalable Causal Consistency for Wide-Area Storage with COPS - Wyatt Lloyd et. al. (2011)
• Logoot-Undo: Distributed Collaborative Editing System on P2P Networks - Stéphane Weiss et. al. (2010)
• Logoot: A Scalable Optimistic Replication Algorithm for Collaborative Editing on P2P Networks - Stéphane Weiss et. al. (2009)
• TreeDoc: A commutative replicated data type for cooperative editing - Nuno Preguiça et. al. (2009)
• WOOT: Real time group editors without Operational transformation - Gérald Oster et. al. (2005)

Clocks

• Dotted Version Vectors: Logical Clocks for Eventually Consistent Systems

Proof and Verification

• A framework for verifying Conflict-free Replicated Data Types (CRDTs) - Dominic Mulligan (2017)
• Verifying Strong Eventual Consistency in Distributed Systems - Victor B. F. Gomes (2017)
• On Verifying Causal Consistency - Bouajjani et. al. (2017)

Blogs

• CRDTs: Theory and Practice (2025)
• Serverless collaboration (2019)
• Good Spirits: Syncing Data Statelessly (2018)
• Data Laced with History: Causal Trees & Operational CRDTs (2018)
• Code together in real time with Teletype for Atom (2017)
• CRDTs explained - supercharge your serverless with CRDTs at the Edge (Russell Sullivan) (2017)
• Working code for Operational Transformation/CRDT hybrid (2017)
• Datanet: a New CRDT Database that Let's You Do Bad Bad Things to Distributed Data (2016)
• Towards a unified theory of Operational Transformation and CRDT (2016)
• Delta State Replicated Data Types (2016)
• A CRDT Primer Part II: Convergent CRDTs (2015)
• A Look at CRDTs (2015)
• Convergent Replicated Data Types (2015)
• Logs and docs (2013)
• Distributed data structures with Coq (2013)

Skepticism

• Why CRDT didn't work out as well for collaborative editing xi-editor (2019)
• Real Differences between OT and CRDT for Co-Editors (2018)

Videos

• CRDTs: The Hard Parts - Martin Kleppman (2020)
• Automerge: Making servers optional for real-time collaboration - Martin Kleppmann (J On The Beach 2018)
• CRDTs for Non Academics (Russell Sullivan) (2017)
• Tutorial: How to build an Collaborative Editing Application with IPFS using CRDT (IPFS) (2017)
• Lightning Talk: Just-Right Consistency: Closing The CAP Gap - Christopher Meiklejohn (Erlang Solutions) (2017)
• Dmitry Ivanov & Nami Naserazad - Practical Demystification of CRDT (Lambda Days 2016) (Erlang Solutions)
• Kappa Day - Practical demystification of CRDT - Tomtom (Jug Łódź) (2016)
• CRDTs in Practice - Marc Shapiro & Nuno Preguiça (Erlang Solutions) (2015)
• ElixirConf 2015 - CRDT: Datatype for the Apocalypse by Alexander Songe (Confreaks)
• "Transactions: myths, surprises and opportunities" by Martin Kleppmann (Strange Loop) (2015)
• "CRDTs Illustrated" by Arnout Engelen (Strange Loop) (2015)
• "Distributed, Eventually Consistent Computations" by Christopher Meiklejohn (Strange Loop) (2015)
• Using Erlang, Riak and the ORSWOT CRDT at bet365 (...) - Michael Owen - Erlang User Conference 2015 (Erlang Solutions)
• Strong Eventual Consistency and CRDTs - Marc Shapiro (ThisByGustav) (2013)
• WOOT: an algorithm for concurrency and collaborative authoring! (Julien Genestoux) (2013)

Playlists

• CRDT (Adib Saikali) (2015-2023)
• crdt (Sonny To) (2015-2020)
• CRDT Talks (IPFS) (2014-2016)

Implementations

• CRDT Code: the exhaustive, continuously updated list of libraries

Data Structures

• json-joy: A high-performance JSON and rich-text CRDT focused on speed and correctness
• KSeq: A continuous sequence CRDT based on Logoot/LSEQ
• LSEQ: CRDT for sequences
• LSEQTree: A data structure for distributed arrays using the LSeq allocation strategy
• LSEQArray: aims to provide an implementation of a CRDT-based array using the allocation strategy LSEQ
• Automerge: A JSON-like data structure (a CRDT) that can be modified concurrently by different users, and merged again automatically
• Yjs: framework for offline-first p2p shared editing on structured data like text, richtext, json, or XML
• RON: Replicated Object Notation, a distributed live data format (implementations in C++, Elixir, Go, Haskell, Java, JavaScript, Rust)
• teletype-crdt: The string-wise sequence CRDT powering peer-to-peer collaborative editing in Teletype for Atom
• Peer CRDT: An extensible collection of operation-based CRDTs that are meant to work over a p2p network
• Distributed Data Structures in Coq
• Akka CRDT: An Eventually Consistent REST/JSON database using CRDTs, Akka Cluster and LevelDB
• Akka Distributed Data
• wurmloch-crdt: Experimental implementations of CRDTs for the JVM
• Ama.CRDT: A C# .NET 10 high-performance, Native AOT-ready library using CRDTs
• Velt: collaboration SDK providing Yjs-based CRDT stores (array, map, text, XML) with hosted sync, presence and offline editing
• Loro: CRDT library inspired by Event Graph Walker (for Rust, JavaScript and Swift)

Toy Implementations

• Companion to the article "Data Laced with History: Causal Trees & Operational CRDTs"
• Meangirls: Convergent Replicated Data Types

Text Editors

• mutxt.com: a polished local-first rich-text editor based on json-joy Peritext CRDT, available as a web app and desktop app (npx mu-txt), plus open-source React mutxt-react and Web Component mutxt-element libraries
• SandEdit: a project aiming to provide a distributed collaborative editor based on CRDTs
• Teletype for Atom: Share your workspace with team members and collaborate on code in real time in Atom
• Xi Editor: an attempt to build a high quality text editor, using modern software engineering techniques
• IPFS CRDT Shared Editing: Decentralized Real-Time Collaborative Documents - Conflict-free editing in the browser using js-IPFS and CRDTs
• Shared editing demo using IPFS and CRDT
• Co: collaborative text editor, uses woot. front end in Elm, back in node
• woot-collaborative-editor: A real time collaboration toy project based on WOOT. Implemented with node.js and ws
• cljs-collab: Browser-to-browser collaborative editor
• Xray: An experimental next-generation Electron-based text editor

Databases and Logs

• AntidoteDB: planet scale, highly available, transactional database
• Riak KV: distributed NoSQL database designed to deliver maximum data availability by distributing data across multiple servers
• Hypermerge: combines Automerge, a CRDT, with hypercore, a distributed append-only log
• Roshi: a large-scale CRDT set implementation for timestamped events
• Swarm: JavaScript replicated model (M of MVC) library
• Datanet: an open source CRDT based data synchronization system
• Kuhirō: The Near Cloud
• Artel: CRDT-based memory replication across self-hosted instances over JSON Feed, no central coordinator
• Yorkie: a document store for building collaborative editing applications
• ZamSync: offline-first WAL sync engine in Rust using Hybrid Logical Clocks and Version Vectors for causal ordering and deduplication

Productivity

• ff: a distributed note taker and task manager

More Lists

• Readings in CRDTs
• Carlos Baquero bibliography
• BOOM: Berkley Orders of Magnitude
• CRDT Resources: talks, blog posts and courses, collected by crdt.tech