Angular Signals: Complete 2025 Guide to the New Reactive State Model

Modern Angular development is evolving rapidly, and one of the biggest breakthroughs in 2025 is the introduction of Angular Signals—a simpler, faster, and more predictable way to manage reactive state. Whether you’re a beginner or an experienced Angular developer, Signals make your code cleaner, more readable, and significantly more performant.

In this complete guide, we break down what Angular Signals are, how they work, why Angular introduced them, performance benefits, real use cases, limitations, examples, and comparisons with RxJS.

This blog post is beginner-friendly and perfect for developers preparing for interviews or migrating to the modern Angular reactivity model.

Introduction to Angular Signals

Reactive programming has always been at the heart of Angular. For years, developers relied heavily on RxJS Observables, async pipes, and change detection strategies. While powerful, RxJS can often feel overwhelming to beginners and unnecessarily complex for simple UI state updates.

This is why Angular introduced Signals—a new reactive primitive that focuses on:

• Synchronous state changes
• Fine-grained reactivity
• Better performance
• Cleaner and predictable state management

Signals simplify everything from counter apps to complex UI logic by providing a direct and intuitive way to manage state.

What Are Signals in Angular?

Angular Signals are a new mechanism for storing, updating, and reacting to data changes without relying on heavy RxJS streams.
They act like reactive variables that automatically notify Angular when values change.

Key Features of Signals

• They are synchronous
• They re-render only the exact parts of the UI that depend on them
• They track dependencies automatically
• They replace many use cases of RxJS for local component state

Angular Signals come in two main types:

• Writable Signals
• Computed Signals

Let’s break them down.

2.1 Writable Signals

Writable signals store a value that can be read, updated, or reset.

Example: Writable Signal

import { signal } from '@angular/core';

count = signal(0);

increase() {
  this.count.update(c => c + 1);
}

This is simpler, easier to maintain, and more beginner-friendly than using BehaviorSubjects or RxJS streams.

2.2 Computed Signals

Computed signals derive new values based on one or more existing signals.

Example: Computed Signal

fullName = computed(() => this.firstName() + ' ' + this.lastName());

Angular automatically recalculates fullName when either firstName or lastName changes.

No manual subscriptions.
No unsubscribe logic.
No boilerplate.

Why Angular Introduced Signals?

Angular introduced signals to solve three major problems in traditional development:

Performance Benefits:

Angular Signals offer fine-grained reactivity, meaning only the smallest affected part of the UI re-renders when needed.

This leads to:

• Faster rendering
• Lower CPU usage
• Efficient change detection
• Smooth UI even in large applications

In benchmarks, Signals outperform typical Observable-based UI updates for local state, making them ideal for interactive dashboards, counters, forms, and filters.

Cleaner and Simpler Code

With Signals:

• No need for subscribe()
• No need for async pipe everywhere
• No need for ngOnDestroy or manual unsubscription
• No need for complex RxJS operators

Developers can now manage component state with simple, readable code that beginners can understand.

Predictable State Management

Signals follow a predictable data flow pattern—read → compute → update.

This removes the unpredictability of async streams and helps developers avoid memory leaks and unexpected state changes.

Signals also improve debugging since they behave like simple variables.

How To Use Signals in Angular

Now let’s explore real examples that you can use in your applications.

Basic writable signal

import { Component, signal } from '@angular/core';

@Component({
  selector: 'app-counter',
  template: `
    <h2>{{ count() }}</h2>
    <button (click)="increase()">Increase</button>
  `
})
export class CounterComponent {
  count = signal(0);

  increase() {
    this.count.update(c => c + 1);
  }
}

Produces:

• Superfast updates
• Zero change detection overhead
• Perfect for UI counters, toggles, loaders

Computed signal example

fullName = computed(() => this.firstName() + ' ' + this.lastName());

This is ideal for derived state like:

• Calculating totals
• Combining values
• Dynamic UI calculations

Shared state using service signals

Signals can be created inside services and shared across components.

@Injectable({ providedIn: 'root' })
export class UserService {
  user = signal({ name: 'John', age: 25 });
}

Works great for:

• Theme management
• Cart state in e-commerce
• Auth user state
• Dashboard filters

Angular Signals vs RxJS — Key Differences

Many developers want to know whether Signals replace RxJS.
The answer: No — they complement each other.

When to use Signals

Use Signals when working with:

• Local component state
• UI values
• Counters and toggles
• Derived state
• Reactive forms
• Shared non-async state
• Performance-sensitive UI components

When RxJS is still better

Use RxJS for:

• HTTP requests
• WebSockets
• User input streams
• Debouncing & throttling
• Event streams
• Background tasks
• Multicasting

RxJS remains essential for asynchronous and event-driven programming.

Real Use Cases of Angular Signals in 2025

Here are practical real-world scenarios where Signals shine:

✔ State of active tab or UI element

Ideal for user-driven UI updates.

✔ Cart quantity updates in eCommerce

Smooth, instant UI rendering.

✔ Form validation logic

No subscriptions needed.

✔ Dashboard analytics widgets

Fast and optimized updates.

✔ Theme switcher (dark/light)

Instant UI re-render without performance loss.

✔ Local counters, filters, and toggles

A perfect RxJS alternative for these cases.

✔ Derived state like totals, discount calculations, dynamic labels

Computed signals simplify business logic drastically.

Limitations of Angular Signals

Even though Signals are powerful, they are not perfect.

Key Limitations

• Not suitable for asynchronous streams
• Cannot fully replace RxJS
• Best for local state but not large-scale global state
• Computed signals cannot have side effects
• Must avoid overusing computed signals to prevent cascading updates

Understanding when NOT to use signals is as important as knowing when to use them.

Conclusion

Angular Signals mark a major milestone in the evolution of modern Angular development. With cleaner code, improved performance, predictable state management, and beginner-friendly syntax, Signals are quickly becoming the default choice for handling UI state in Angular applications.

While RxJS remains essential for async streams, Signals are now the best solution for local, synchronous, and UI-focused state updates.

If you’re building Angular apps in 2025, learning Signals is no longer optional—it’s the future of Angular reactivity.

Related Posts:

Angular Signals Overview

Angular Components Tutorial

FAQ

Q1. What are Angular Signals?
Angular Signals are reactive primitives used to track and update state efficiently in Angular apps.

Q2. Are Signals better than RxJS?
Signals simplify local state, while RxJS remains ideal for asynchronous streams and complex reactive flows.

Q3. Do Angular Signals replace NgRx?
No. NgRx is still used for large-scale state, but Signals can be used for local and derived state.

Q4. What are computed signals?
Computed signals derive values automatically based on other signals.

Q5. Should I start using Signals in new projects?
Yes. For new Angular apps, Signals provide simpler reactivity, cleaner code, and better performance.