Introduction

Self-hosted real-time CRDT store. No locks, no merge conflicts.

Meridian is a self-hosted alternative to Liveblocks and PartyKit. Concurrent updates from multiple clients converge automatically using CRDTs — no operational transforms, no conflict resolution code on your end.

Sub-millisecond merge latency on a single node. Deltas are broadcast over WebSocket as soon as an op is applied — no polling, no round-trips.

Live demo

Open the collaborative workspace demo — try it in two browser tabs simultaneously.

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What it is

• Server: Rust binary. Embedded sled storage by default — PostgreSQL and Redis backends available as optional features.
• SDKs: TypeScript (Effect-based, msgpack), Python (asyncio, pip install meridian-crdt), Rust (meridian-client).
• Auth: Custom ed25519-signed tokens (smaller than JWT, constant-time verification).
• Query Engine: Cross-CRDT queries — scan a namespace by glob pattern, filter, and aggregate (sum, union, latest, …) in a single HTTP request.

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Quickstart

1. Start the server

MERIDIAN_SIGNING_KEY=$(openssl rand -hex 32) docker compose up -d

2. Install the SDK

bun add meridian-sdk

3. Connect and sync

import { Effect, Schema } from "effect";
import { MeridianClient } from "meridian-sdk";

const client = await Effect.runPromise(
  MeridianClient.create({
    url: "http://localhost:3000",
    namespace: "my-room",
    token: process.env.MERIDIAN_TOKEN!,
  })
);

const views = client.gcounter("gc:views");
views.increment(1);
views.onChange(v => console.log("views:", v));

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CRDT types

Type	Use case
GCounter	Page views, likes, download counts
PNCounter	Inventory, vote tallies
ORSet	Shopping cart, tag sets, collaborative lists
LwwRegister	User profile, document title, config
Presence	Who’s online, cursor positions, typing indicators
CRDTMap	Structured document with independent typed fields
Awareness	Ephemeral cursors, selections, “is typing” — not persisted
RGA	Collaborative text, ordered lists
Tree	Hierarchical structures, outlines, file trees