This is a very important architectural decision in Gutenberg — and honestly, many developers misuse both.

Let’s break it down in a practical, real-world way so you can decide like a tech lead 👇

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🧠 select('core') vs apiFetch — What’s the Difference?

Feature	select('core')	apiFetch
Data Source	WP Data Store (core-data)	Direct REST API
Reactivity	✅ Reactive (auto re-render)	❌ Not reactive
Caching	✅ Built-in caching	❌ No caching
Performance	✅ Optimized	⚠️ Depends on usage
Ease of Use	✅ Cleaner in blocks	⚠️ More manual
Control	⚠️ Limited	✅ Full control

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✅ When You Should Use select('core') (Recommended Most of the Time)

👉 Use this inside Gutenberg blocks/UI

✔ Best for:

• Fetching posts, pages, users
• Displaying dynamic data in UI
• When you want automatic updates
• When performance matters

Example

const posts = useSelect((select) => {
    return select('core').getEntityRecords('postType', 'post');
}, []);

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💡 Why it’s better

• Uses centralized state (Redux-like store)
• Avoids duplicate API calls
• Auto re-renders UI when data changes
• Works seamlessly with Gutenberg

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⚠️ When apiFetch is Better

👉 Use this when you need full control or custom behavior

✔ Best for:

• Custom REST API endpoints
• POST / PUT / DELETE requests
• Non-Gutenberg environments
• One-time operations (form submit, migration scripts, etc.)

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Example

import apiFetch from '@wordpress/api-fetch';const fetchData = async () => {
    const posts = await apiFetch({
        path: '/wp/v2/posts?per_page=5',
    });    console.log(posts);
};

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🚨 Common Mistake (Very Important)

❌ Using apiFetch inside React render logic:

// ❌ BAD PRACTICE
const posts = await apiFetch({ path: '/wp/v2/posts' });

👉 This causes:

• Multiple API calls
• No caching
• Performance issues

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⚡ Real-World Decision Rule (Use This)

👉 Ask yourself:

1. Is this UI data inside Gutenberg?

👉 ✅ Use select('core')

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2. Is this a custom API or action (POST/UPDATE)?

👉 ✅ Use apiFetch

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3. Do I need caching + reactivity?

👉 ✅ Use select('core')

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4. Do I need full control over request?

👉 ✅ Use apiFetch

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🏆 Best Practice (Senior-Level Pattern)

👉 Combine both when needed:

• Use select('core') → for reading data
• Use apiFetch → for writing/updating data

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Example Pattern

// Read (cached + reactive)
const posts = useSelect((select) =>
    select('core').getEntityRecords('postType', 'post')
);// Write (manual control)
const createPost = async () => {
    await apiFetch({
        path: '/wp/v2/posts',
        method: 'POST',
        data: { title: 'New Post' },
    });
};

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🧩 Bonus Insight (Interview-Level)

👉 select('core') internally:

• Uses @wordpress/core-data
• Wraps REST API calls
• Adds caching + resolution tracking
• Prevents duplicate requests

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🏁 Final Verdict

👉 If you’re building Gutenberg blocks:

Use select('core') 80–90% of the time

👉 Use apiFetch only when:

• You need custom logic
• Or you’re mutating data