TodayTools

Firebase flashcards

Google's ready-made backend: Firestore, sign-in, storage, functions, hosting and push, with rules to keep data safe.

Donate
Beginner friendly, starts from zero
Section
How to study
0
FirebaseStart from zero · 1 of 11

What is Firebase, in one plain sentence?

Firebase is a set of ready-made online services from Google that give your app a database, sign-in, file storage and hosting, so you do not have to build and run your own server.

Firebase is a rented back office for your app.
Show again
11 left
Got it

Tap to turn over. Swipe right if you know it, left to see it again.

All topics

What you will learn

  1. Start from zero

    • What Firebase is and why4 cards
    • First words and setup7 cards

  2. Core basics

    • Firestore reads and writes8 cards
    • Sign-in3 cards
    • First security rules and storage2 cards
    • Choosing services, hosting and cost4 cards

  3. Next steps

    • Data modelling4 cards
    • Safe concurrent writes3 cards
    • Rules and roles3 cards
    • Cloud Functions3 cards
    • Local testing, offline and protection4 cards

  4. Go deeper

    • Scale and indexes3 cards
    • Advanced rules2 cards
    • Reliable functions3 cards
    • Beyond Firestore4 cards
    • Operations, cost and architecture5 cards

Final test and certificate

10 questions drawn fresh from the whole topic, about 15 minutes. Sign in, score 80% or more and get a free certificate with your name and a public check link anyone can open, such as an employer or a teacher. Not signed in? Try a practice test from the cards.

Take the final test

About these cards

  • Reviewed 26 October 2026
  • CoversFirebase JS SDK 12 (modular)Cloud Functions 2nd genFirestore rules_version 2
How these cards are made

Firebase at a glance

Firebase gives your app a ready-made backend from Google: a live database, sign-in, file storage, server functions and hosting.

Firebase is a rented back office: filing cabinets, a front-desk guard and a mail room, all run for you.

Words you will meet

Backend
The part of an app on the internet that keeps everyone's data
Collection
A named group of similar records, like orders
Document
One record with an ID and labelled fields
Authentication
Checking who someone is when they sign in
Security rules
Instructions that decide who may read or change data
Cloud function
Your own code that Google runs when something happens
Console
The website where you manage your Firebase project

The steps

  1. 1. Start from zero (11 cards): What Firebase is, what a backend does, and the words you need before building your first app.
  2. 2. Core basics (17 cards): Connecting, Firestore reads and writes, queries, live updates, sign-in, first rules, storage, hosting and pricing.
  3. 3. Next steps (17 cards): Data modelling, transactions, batches, paging, rules validation, claims, Cloud Functions, secrets, emulators and App Check.
  4. 4. Go deeper (17 cards): Indexes, hotspots, rules internals, cold starts, idempotent triggers, search, AI Logic, cost control and backups.
All 11 cards in Start from zero
What is Firebase, in one plain sentence?
Firebase is a set of ready-made online services from Google that give your app a database, sign-in, file storage and hosting, so you do not have to build and run your own server.
What is a backend, and why does an app need one?
The backend is the part of an app that lives on the internet, not on your phone. It keeps everyone's data, checks who is signed in, and lets two phones see the same chat or order.
Where do you meet Firebase-powered apps in daily life?
Chat apps that update instantly, games that save your progress, small business booking apps, and the notifications many apps send to your phone often use Firebase.
Give an everyday picture of the Firestore database.
Think of a filing cabinet. Each drawer is a collection, like "orders". Each folder inside is a document, like one order, holding labelled facts such as total and status.
Key words: what are a collection and a document?
A collection is a named group of similar records, like users. A document is one record in it with an ID and fields, like user rahul_42 with name and city.
Key word: what is authentication?
Authentication means checking who someone is, like signing in with Google, email or a phone number code. Firebase Authentication does this part for you.
Key words: what are security rules?
Rules are short instructions stored in Firebase that decide who may read or change each piece of data, like "only the owner can see their own orders".
Key words: what are a project and the console?
A Firebase project is the container for one app's services and data. The console is the website where you create the project, look at data and change settings.
Key word: what is a cloud function?
A small piece of your own code that Firebase runs on Google's servers when something happens, like sending a welcome email when a user signs up. You never manage the server.
What do you need before starting with Firebase?
A Google account, basic JavaScript (or Flutter, Swift or Kotlin for mobile), and Node.js for the Firebase command line tool.
What will you be able to do after this topic?
Build an app with sign-in, a live Firestore database, file uploads, safe security rules, cloud functions and hosting, test it all locally, and keep costs low.
Firebase cheatsheet

Firestore

  • doc(db, 'orders', id) Reference a document
  • addDoc(collection(db, 'x'), data) Create with auto ID
  • setDoc(ref, data, { merge: true }) Create or merge
  • updateDoc(ref, { a: 1 }) Change fields
  • getDocs(query(...)) Run a query once
  • onSnapshot(q, cb) Live updates
  • increment(1) / serverTimestamp() Server-side values

Queries

  • where('status', '==', 'new') Filter
  • orderBy('createdAt', 'desc') Sort
  • limit(20) Page size
  • startAfter(lastDoc) Next page
  • getCountFromServer(q) Count cheaply

Auth

  • signInWithPopup(auth, provider) Google sign-in
  • createUserWithEmailAndPassword Email sign-up
  • onAuthStateChanged(auth, cb) Watch sign-in state
  • signOut(auth) Sign out
  • setCustomUserClaims(uid, {...}) Roles (Admin SDK)

Rules

  • request.auth.uid Caller's user ID
  • resource.data Stored document
  • request.resource.data Incoming write
  • get(/databases/$(database)/documents/...) Read another doc
  • keys().hasOnly([...]) Allowed fields

CLI

  • firebase init Set up services
  • firebase emulators:start Run locally
  • firebase deploy --only hosting Deploy site
  • firebase deploy --only firestore:rules Deploy rules
  • firebase deploy --only functions Deploy functions
  • firebase use prod Switch project
Donate