Building your own sync engine means retries, conflicts, and edge cases that bite back. RxDB ships the sync engine: replication to any backend, conflict handling, and offline support in one database.
RxDB's easy-to-use Sync Engine powers realtime synchronization between JavaScript clients and servers. Either use one of our prebuild replication plugins...
OR
...sync with your custom server by implementing only three simple endpoints.
RxDB adopts the local-first approach by storing data locally on the JavaScript client and managing continuous synchronization. You can even run your app entirely without a backend.
RxDB uses JSON Schema, a format widely recognized by developers through tools like OpenAPI or Swagger. Because JSON Schema is so well-established, it integrates seamlessly with existing validators, editors, and development tooling, making schema design both simple and highly flexible.
A minimal RxDB schema might define fields, data types, and indexes in a fully declarative way. For example:
const heroSchema = {
title: 'hero schema',
version: 0,
primaryKey: 'id',
type: 'object',
properties: {
id: {
type: 'string',
maxLength: 100
},
name: {
type: 'string'
},
power: {
type: 'string'
},
age: {
type: 'number'
}
},
required: ['id', 'name']
};
