Make your JSON data collaborative and version-controlled π¦
Documentation
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Getting Started
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Rust Doc
β¨ Loro 1.0 is out! Read the announcement.
Loro is a [CRDTs(Conflict-free Replicated Data Types)](https://crdt.tech/) library that makes building [local-first][local-first] and collaborative apps easier. You can now use it in Rust, JS (via WASM), and Swift.
# Features
**Features Provided by CRDTs**
- P2P Synchronization
- Automatic Merging
- Local Availability
- Scalability
- Delta Updates
**Supported CRDT Algorithms**
- π Text Editing with [Fugue]
- π [Rich Text CRDT](https://loro.dev/blog/loro-richtext)
- π² [Moveable Tree](https://loro.dev/docs/tutorial/tree)
- π [Moveable List](https://loro.dev/docs/tutorial/list)
- πΊοΈ [Last-Write-Wins Map](https://loro.dev/docs/tutorial/map)
**Advanced Features in Loro**
- π [Fast Document Loading](https://loro.dev/blog/v1.0)
- β±οΈ Fast [Time Travel](https://loro.dev/docs/tutorial/time_travel) Through History
- ποΈ [Version Control with Real-Time Collaboration](https://loro.dev/blog/v1.0#version-control)
- π¦ [Shallow Snapshot](https://loro.dev/docs/advanced/shallow_snapshot) that Works like Git Shallow Clone
> In this example, we demonstrate importing an entire Loro codebase into a Loro-powered
> version controller, preserving the complete Git DAG history while enabling fast version switching.
## Debugging the Wasm build
The standard build pipeline (`deno run -A ./scripts/build.ts dev|release`) now keeps DWARF debugging information through `wasm-bindgen` and emits two helper files alongside every `loro_wasm_bg.wasm` artifact:
- `loro_wasm_bg.wasm.map` — a v3 source map derived from DWARF so that Chrome, Edge, and Firefox can show original Rust locations when inspecting stack traces.
Load the source map in browser devtools; when devtools fetches the debug companion it can map instructions back to Rust source files and line numbers without inflating the shipped `.wasm`.
# Example
[](https://stackblitz.com/edit/loro-basic-test?file=test%2Floro-sync.test.ts)
```ts
import { expect, test } from 'vitest';
import { LoroDoc, LoroList } from 'loro-crdt';
test('sync example', () => {
// Sync two docs with two rounds of exchanges
// Initialize document A
const docA = new LoroDoc();
const listA: LoroList = docA.getList('list');
listA.insert(0, 'A');
listA.insert(1, 'B');
listA.insert(2, 'C');
// Export all updates from docA
const bytes: Uint8Array = docA.export({ mode: 'update' });
// Simulate sending `bytes` across the network to another peer, B
const docB = new LoroDoc();
// Peer B imports the updates from A
docB.import(bytes);
// B's state matches A's state
expect(docB.toJSON()).toStrictEqual({
list: ['A', 'B', 'C'],
});
// Get the current version of docB
const version = docB.oplogVersion();
// Simulate editing at B: delete item 'B'
const listB: LoroList = docB.getList('list');
listB.delete(1, 1);
// Export the updates from B since the last sync point
const bytesB: Uint8Array = docB.export({ mode: 'update', from: version });
// Simulate sending `bytesB` back across the network to A
// A imports the updates from B
docA.import(bytesB);
// A has the same state as B
expect(docA.toJSON()).toStrictEqual({
list: ['A', 'C'],
});
});
```
# Blog
- [Loro 1.0](https://loro.dev/blog/v1.0)
- [Movable tree CRDTs and Loro's implementation](https://loro.dev/blog/movable-tree)
- [Introduction to Loro's Rich Text CRDT](https://loro.dev/blog/loro-richtext)
- [Loro: Reimagine State Management with CRDTs](https://loro.dev/blog/loro-now-open-source)
# Credits
Loro draws inspiration from the innovative work of the following projects and individuals:
- [Diamond-types](https://github.com/josephg/diamond-types): The [Event Graph Walker (Eg-walker)](https://loro.dev/docs/advanced/event_graph_walker) algorithm from @josephg has been adapted to reduce the computation and space usage of CRDTs.
- [Automerge](https://github.com/automerge/automerge): Their use of columnar encoding for CRDTs has informed our strategies for efficient data encoding.
- [Yjs](https://github.com/yjs/yjs): We have incorporated a similar algorithm for effectively merging collaborative editing operations, thanks to their pioneering work.
- [Matthew Weidner](https://mattweidner.com/): His work on the [Fugue](https://arxiv.org/abs/2305.00583) algorithm has been invaluable, enhancing our text editing capabilities.
- [Martin Kleppmann](https://martin.kleppmann.com/): His work on CRDTs has significantly influenced our comprehension of the field.
[local-first]: https://www.inkandswitch.com/local-first/
[Fugue]: https://arxiv.org/abs/2305.00583