If you've been building with React for a while, you're likely familiar with hooks like useState, useEffect, or useRef. But there's one lesser-known hook that quietly does a lot of heavy lifting — kind of like the right Ctrl key on your keyboard that no one really uses: useId().

In this post, we’ll explore what useId() actually does, when to use it, and how it can help improve both the structure and accessibility of your components.

🤔 What Exactly Is useId()?

Introduced in React 18, useId() is a built-in hook that generates unique, consistent IDs for your components.

It’s particularly useful for things like:

• Linking <label>s to <input>s
• ARIA attributes for accessibility
• Avoiding duplicate IDs in dynamic UI structures

Unlike manually generating IDs using Math.random() or Date.now(), useId() ensures that IDs are stable between renders and unique across the entire app — both on the client and the server.

🧠 Why Should You Care?

Before React 18, developers often had to create their own solutions to generate unique IDs. Now, with useId(), things are way simpler — and safer.

✅ Benefits of useId():

• Avoids Duplicate IDs: Hardcoding IDs can easily lead to duplication. useId() ensures uniqueness automatically.
• SSR + CSR Consistency: Guarantees that your IDs stay the same whether the component is rendered on the server or client.
• Boosts Accessibility: Perfect for ARIA labels and linking elements together in an a11y-friendly way.

🛠 How to Use useId() in React

Let’s see a basic example:

import { useId } from 'react';

function CustomInput() {
  const id = useId();

  return (
    <div>
      <label htmlFor={id}>Enter your name:</label>
      <input id={id} type="text" placeholder="John Doe" />
    </div>
  );
}

export default CustomInput;

Here, useId() generates a consistent ID that links the <label> and <input> together.

🔁 Need More Than One ID?

Sometimes you’ll need multiple unique IDs in a single component — no problem:

import { useId } from 'react';

function CustomForm() {
  const nameId = useId();
  const emailId = useId();

  return (
    <form>
      <div>
        <label htmlFor={nameId}>Name:</label>
        <input id={nameId} type="text" placeholder="John Doe" />
      </div>
      <div>
        <label htmlFor={emailId}>Email:</label>
        <input id={emailId} type="email" placeholder="john@example.com" />
      </div>
    </form>
  );
}

export default CustomForm;

Each call to useId() returns a new unique ID — super helpful when building reusable forms or dynamic UIs.

♿ Improving Accessibility with useId()

Accessibility (a11y) is a core part of modern web development. With useId(), you can easily manage ARIA attributes and relationships.

Here, the heading is clearly linked to the alert container, improving the screen reader experience.

🚫 When Not to Use useId()

Although useId() is powerful, it’s not always the right tool. Here are some cases where it’s better to skip it:

List Keys: Don’t use useId() for keys in lists — instead, rely on unique data from your items.

User-Generated IDs: If the ID comes from a database or API, you don’t need useId().

Per-Render Needs: If the ID changes every render (e.g., for animations), go with useRef() or state instead.

✅ Final Thoughts
useId() is a simple but powerful addition to the React Hooks family. It helps keep your components accessible, avoids bugs with duplicate IDs, and works seamlessly with SSR.

Start using it where appropriate — especially in forms and accessibility-related scenarios — and you’ll write cleaner, more resilient components.

Happy coding!