Angular Version 21 Upgrade Example

Source: Dev.to

Overview

This Angular web application was the first one I developed as a self‑directed study in 2020. It has been upgraded regularly since its Angular 8 inception and was recently migrated from Angular 20 to Angular 21. The live demo can be viewed at .

Performance Improvements

• New applications use zoneless change detection by default.
• Build optimizations, such as esbuild/Vite integration, lead to:
  • Faster application rendering
  • Smaller bundle sizes (up to 40 % reduction)
  • Quicker build times

Simplified Reactivity with Signals

• Signals are fully integrated, offering a straightforward method to manage state.
• This reduces the need for complex RxJS patterns for basic UI updates, simplifying the developer experience.

Enhanced Server‑Side Rendering (SSR) & SEO

• Improvements to SSR and hydration, including SSR streaming and faster hydration, result in:
  • Better Core Web Vitals
  • Improved SEO
  • A smoother user experience