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home / developersection / interviews / what is the difference between angular cli 14/15/16 and cli 21?
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Anubhav Sharma
Anubhav Sharma

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The Anubhav portal was launched in March 2015 at the behest of the Hon'ble Prime Minister for retiring government officials to leave a record of their experiences while in Govt service .

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1 Answers

Anubhav Sharma
Anubhav Sharma 01 Dec 2025
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The Core Difference

  • Angular CLI 14/15/16 = Old Angular ecosystem (pre-standalone)
  • Angular CLI 21 = Modern Angular ecosystem (standalone-first, buildless, faster compilation, much smaller bundles)

Major Differences (Simple & Clear)

Standalone vs. NgModule

CLI 14/15/16

  • Still required NgModule (AppModule, FeatureModule, etc.)
  • Standalone components introduced (v14) but optional.
  • CLI generated code used NgModules.

CLI 21

  • Fully Standalone-first.
  • CLI generates standalone components by default.
  • NgModule no longer needed.

Example (CLI 21):

ng generate component home

→ Creates a standalone component automatically.

Build System (Legacy Webpack → New Build Tools)

CLI 14/15/16

  • Used Webpack-based Angular build system.
  • Slower builds.
  • Larger bundles.

CLI 21

  • Uses ESBuild + Vite under the hood.
  • MUCH FASTER:
    • 2–10× faster builds
    • Instant HMR (Hot Module Reload)
    • Smaller production bundles

Signals & Reactivity

CLI 14/15/16

  1. Used Zone.js + RxJS for change detection.
  2. No Signals support.

CLI 21

  • Signals are now part of the Angular reactivity model.
  • Optional zoneless apps (no Zone.js needed).

Routing (simplified)

CLI 14/15/16

  • Routing required Modules → RouterModule.forRoot()

CLI 21

Routing without modules:

export const routes = [
  { path: '', component: HomeComponent }
];

Server-Side Rendering (SSR) / Hydration

CLI 14/15/16

  • SSR existed but heavy and complex.
  • No full hydration support.

CLI 21

  • SSR + CSR Hybrid (Universal + Vite)
  • Full hydration out of the box → faster interaction.

TypeScript Version

CLI 14/15/16

  • TS 4.7 → 4.9

CLI 21

  • Uses TypeScript 5.x
  • Major performance boost & new TS features.

Developer Experience (DX) Boost

CLI 14/15/16

  • Basic HMR.
  • Slower dev server.
  • Slower unit tests.

CLI 21

  • Lightning-fast dev server
  • Near-instant reloads
  • ESBuild test runner (super fast)
  • Simplified project structure

Optional Features

Feature CLI 14–16 CLI 21
Standalone components Partial Default
Signals No Yes
Zone-less mode No Yes
Hydration No Yes
Vite No Yes
ESBuild No Yes
NgModules Required Optional (legacy)

Summary for Interview

Angular CLI 21 is a modern, standalone-first, Vite-powered CLI with faster builds, zoneless reactivity via signals, better SSR hydration, and simplified routing.


Angular CLI 14/15/16 relied on NgModules, Webpack builds, slower HMR, and no Signals support.

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