Firebase Cheat Sheet

Updated 2026-04-29

Firebase is Google's comprehensive backend-as-a-service (BaaS) platform that provides cloud infrastructure, databases, authentication, hosting, serverless functions, AI capabilities, and analytics for mobile and web applications. Firebase eliminates the need to build and manage backend infrastructure from scratch, offering real-time synchronization, automatic scaling, and deep integration with Google Cloud. In 2026, the platform has significantly expanded with Firebase App Hosting for full-stack web apps, Firebase AI Logic for client-side Gemini API access, Firebase SQL Connect (formerly Data Connect) for PostgreSQL integration, and Firestore pipeline queries with full-text and geospatial search — making it a comprehensive platform for both traditional and AI-powered applications.

What This Cheat Sheet Covers

This topic spans 26 focused tables and 237 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.

Table 1: Project Setup and ConfigurationTable 2: Firebase Authentication MethodsTable 3: Firestore Database OperationsTable 4: Firestore Security RulesTable 5: Firebase Cloud Functions TriggersTable 6: Firebase HostingTable 7: Firebase App HostingTable 8: Firebase StorageTable 9: Firebase SQL Connect (formerly Data Connect)Table 10: Firebase Cloud Messaging (FCM)Table 11: Remote ConfigTable 12: Firebase ExtensionsTable 13: Realtime Database OperationsTable 14: Firebase AnalyticsTable 15: Firebase Performance MonitoringTable 16: Firebase CrashlyticsTable 17: Firebase App DistributionTable 18: Firebase Test LabTable 19: Firebase ML KitTable 20: Firebase AI LogicTable 21: Firebase GenkitTable 22: Pricing PlansTable 23: Firebase CLI CommandsTable 24: Firestore Best PracticesTable 25: Firebase Security Best PracticesTable 26: Firebase Dynamic Links (Legacy)

Table 1: Project Setup and Configuration

Before any Firebase feature works, you have to wire up a project — and that means two distinct setups. The client SDK (initializeApp(config)) runs in browsers and apps under security rules, while the Admin SDK runs on your server with elevated privileges that bypass those rules. The CLI commands and local emulators here are what you use day to day to deploy, switch between dev and production, and develop offline without touching live data.

Method	Example	Description
Initialize Firebase project (CLI)	`firebase init`	• Sets up a new Firebase project in the current directory • prompts to select services (Hosting, App Hosting, Functions, Firestore, etc.) and links to a Firebase project.
Deploy to Firebase	`firebase deploy`	• Deploys all configured services to production • supports partial deployment with `--only` flag (e.g., `--only hosting,functions`).
Initialize SDK (JavaScript)	`import { initializeApp } from 'firebase/app';` `const app = initializeApp(config);`	• Initializes Firebase SDK with project configuration (API key, project ID, app ID) • must be called before using any Firebase services.
Initialize Admin SDK (Node.js)	`const admin = require('firebase-admin');` `admin.initializeApp();`	• Initializes Firebase Admin SDK for server-side operations • bypasses security rules and provides elevated privileges for backend tasks.
Configure service account	`admin.initializeApp({` `credential: admin.credential.cert(key),` `});`	• Authenticates Admin SDK using a service account JSON key • required for server environments without default Application Default Credentials.

Table 1: Project Setup and Configuration

Method	Example	Description
Initialize Firebase project (CLI)	`firebase init`	• Sets up a new Firebase project in the current directory • prompts to select services (Hosting, App Hosting, Functions, Firestore, etc.) and links to a Firebase project.
Deploy to Firebase	`firebase deploy`	• Deploys all configured services to production • supports partial deployment with `--only` flag (e.g., `--only hosting,functions`).
Initialize SDK (JavaScript)	`import { initializeApp } from 'firebase/app';` `const app = initializeApp(config);`	• Initializes Firebase SDK with project configuration (API key, project ID, app ID) • must be called before using any Firebase services.
Initialize Admin SDK (Node.js)	`const admin = require('firebase-admin');` `admin.initializeApp();`	• Initializes Firebase Admin SDK for server-side operations • bypasses security rules and provides elevated privileges for backend tasks.
Configure service account	`admin.initializeApp({` `credential: admin.credential.cert(key),` `});`	• Authenticates Admin SDK using a service account JSON key • required for server environments without default Application Default Credentials.