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Development · Web app

Zero

General-purpose sync engine bringing local-first performance to Postgres web apps

From the Xiry library · Updated 10 October 2026

Visit zero.rocicorp.dev ↗

Zero is a sync engine by Rocicorp that pairs a client-side store with a server-side read replica of your Postgres database. Queries and mutations run client-first for instantaneous reads and writes, while background sync keeps data reactive and consistent across clients without requiring manual state management or custom realtime APIs. It enables developers to build local-first applications like Linear or Figma without having to download the entire database upfront.

What it's for

  • Build local-first web applications with instant UI reads and writes
  • Sync sliced subsets of Postgres data reactively to frontend clients
  • Handle multi-user collaborative editing with automatic background conflict resolution

Features

  • Instant client-first queries that return local cached data immediately
  • Optimistic mutations with automatic handling of server reverts
  • Reactive queries that update the UI when server data changes
  • ZQL streaming query engine to sync only the required slice of data
  • Zero-cache replica layer running directly against standard Postgres databases
  • Full server authority over business logic and user permissions

Pricing

Open source. Open-source and self-hostable; managed Cloud Zero plans start at $30/month (Hobby), $300/month (Professional), and $1,000/month (BYOC)

Details

Type
Web app
Category
Development
Topic
Data Sync
Open source
Yes
Platforms
Web, Code library, Self-hosted
For
Web application developers building fast, reactive, or collaborative apps on top of Postgres
Alternative to
Replicache, ElectricSQL, PowerSync
Tags
local first, sync, postgres, reactivity, database, webdev

Why it was saved

  • @colmtuite, 6 July 2025: Presented as real (built with it, "blew my mind") — worth looking up for building local-first apps with real-time sync and conflict resolution.

Related

Updated