# Zero

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

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.

Website: https://zero.rocicorp.dev/

## What it is 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](https://xiry.app/topics/development.md)
- 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](https://x.com/colmtuite/status/1941718639968649349): 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

- [Supabase Stripe Wrapper](https://xiry.app/resources/supabase-stripe-wrapper): PostgreSQL foreign data wrapper to query and write Stripe data via SQL (Web app, Open source)
- [Hide Next.js Pages with Metadata Robots](https://xiry.app/resources/hide-next-js-pages-with-metadata-robots): Prevent search engines from indexing specific Next.js pages using metadata robots (Tip, Free)
- [hn-search](https://xiry.app/resources/hn-search): Full-text search over 49M Hacker News items using Neon Postgres BM25 (GitHub repo, Open source)
- [hnfaster](https://xiry.app/resources/hnfaster): Fast full-text search across 49M Hacker News items using Postgres BM25 (Web app, Free)
- [How loading.jsx Works with Suspense in Next.js](https://xiry.app/resources/how-loading-jsx-works-with-suspense-in-next-js): Route-level loading.jsx vs granular React Suspense boundaries in Next.js App Router. (Tip, Free)
- [Interactive X Player Card Embedding](https://xiry.app/resources/interactive-x-player-card-embedding): Guide to embedding interactive websites and web apps inside tweets (Tip, Free)

Updated 10 October 2026. Page: https://xiry.app/resources/zero

Make your own library: Xiry takes your saved reels, tweets, Reddit bookmarks and Watch Later videos, makes them searchable and pulls the useful stuff out, like this library. It's invite-only for now; join the waitlist at https://xiry.app/#waitlist.