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Implement collaboration effortlessly. Powered by CRDTs.
Built for local-first software.

ReimagineStateManagementwithCRDTs

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Loro is a high‑performance CRDT library for local‑first, real‑time collaboration.

High Performance

Optimized for memory, CPU, and loading speed with advanced performance primitives.

Rich CRDT Types Support

Turn JSON-like data into collaborative types effortlessly

Real-Time Collaboration with Version Control

Preserve full version history like Git, even during real-time collaboration

Simple and Intuitive API

Designed with developer experience in mind

Who's Using Loro

Latch.bio
Marimo.io
Dora.run
Subset
RoomyRoomy
Nema
ax-semantics
Macro
Lody

Lody

"We use Loro as the document representation for our web-based computational notebook software... This library is a great step forward toward making 'multiplayer' apps the norm."
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Max
Max
Latch.bio
"if you are looking for a real-time collaboration library (based on CRDTs), I highly recommend @loro_dev. it's performant, type-safe, and actively maintained and I've tried them all"
Myles
Myles
Marimo.io
"... Loro has become my top choice due to its comprehensive API for managing versions and changesets, and its thoughtful (yet simple) TypeScript declarations."
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Cole Lawrence
Cole Lawrence
ColeLawrence.com
"Powerful, performant, and well-designed. The best CRDT for anyone building serious collaborative software."
AJ Nandi
AJ Nandi
Subset.so
"After extensive research, we made a big early technology bet on Loro... 10/10 experience to date."
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Oliver Beavers
Oliver Beavers
Stealth Startup
"Loro's API is really nice to use, has excellent performance and features, and the dev team has been extremely helpful and responsive. I highly recommend!"
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Zicklag
Zicklag
roomy.chat

Rich Text Editor Demo

Effortless Document Synchronization,
Even in P2P Environments

import {  } from "loro-crdt";
const  = new ();
const  = new ();
.("text").("Hello!");
.("text").("Hi!");
const :  = .({ : "update" });
const :  = .({ : "update" });
 
// Exchange bytesA and bytesB via any methods
.();
.();
 
// The merge result is consistent
// They should both be "Hello!Hi!" or "Hi!Hello!"
.(.("text").());
.(.("text").());

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What You Can Build

Loro powers the collaborative state layer. You bring UI, auth, storage, and transport.

Collaborative Documents

Docs‑style editors with presence, history, and conflict‑free merges.
→ Tutorial

Design Tools

Figma‑style canvases with lists/trees, undo/redo, and real‑time sync.
→ Tree | Movable List

Data Dashboards

Airtable‑like tables with shared JSON state, snapshots, and history.
→ Persistence

Multiplayer Games

Shared game state with conflict‑free updates and timeline playback.

Chat Applications

Message streams with offline sync, presence, and conflict‑free history.
→ List

Offline‑First Apps

Local‑first state, updates, and merges that sync when online.
→ Sync

Rich CRDTs Algorithm Support

Basic Data Structures

Includes support for MovableList for ordered collections, LWW (Last Write Win) Map for key-value pairs, MovableTree for hierarchical data, and Text for rich text manipulation, enabling various of applications.

Text/List Editing with Fugue

Loro integrates Fugue, a novel CRDT algorithm designed to minimize the interleaving anomalies when merging concurrent text/list edits.

Rich Text CRDT

Loro manages rich text CRDTs that excel at merging concurrent rich text style edits, maintaining the original intent of each user's input as much as possible. Please read our blog, Loro's Rich Text CRDT, to learn more.

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