Data & Analytics

Firebase Firestore

Build real-time applications with Firebase Firestore NoSQL database, offline sync, and security rules.

Claude Code Cursor Copilot Windsurf

Overview

Cloud Firestore is a flexible, scalable NoSQL database from Firebase/Google Cloud for mobile, web, and server development. It stores data in documents organized into collections, with support for nested subcollections. Firestore provides real-time listeners that sync data across clients instantly, with built-in offline support that caches data locally and syncs when connectivity is restored.

Firestore queries support filtering, ordering, pagination with cursors, and collection group queries that span subcollections. Unlike traditional NoSQL databases, Firestore guarantees strong consistency for all reads. Security rules written in a custom language control read/write access at the document level, evaluated server-side for every operation.

The Firebase SDK provides both client-side (Web, iOS, Android) and server-side (Admin SDK) libraries. The Admin SDK bypasses security rules and provides elevated privileges for backend operations. Firestore integrates with other Firebase services including Authentication, Cloud Functions (triggered by database events), and Firebase Hosting. Pricing is based on document reads, writes, and deletes rather than compute time.

Who Is This For?

Build a real-time chat application with message sync
Implement offline-first mobile app with local caching
Set up Firestore security rules for user data isolation
Trigger Cloud Functions on document create/update/delete

Installation

Setup for Claude Code

npm install firebase

Configuration

import { initializeApp } from "firebase/app"
import { getFirestore, collection, query, where, onSnapshot } from "firebase/firestore"

const app = initializeApp({
  apiKey: process.env.FIREBASE_API_KEY,
  projectId: process.env.FIREBASE_PROJECT_ID,
})

const db = getFirestore(app)

// Real-time listener
const q = query(collection(db, "messages"), where("room", "==", roomId))
onSnapshot(q, (snapshot) => {
  snapshot.docChanges().forEach((change) => {
    if (change.type === "added") console.log("New:", change.doc.data())
  })
})