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HomeToolsTailwind CSS v3 → v4 Config Migrator

Developer utility

• Updated Feb 22, 2026

Tailwind CSS v3 → v4 Config Migrator

Automatically convert your tailwind.config.js (v3) to the new Tailwind CSS v4 CSS-first @theme {} syntax. Instant, free, and 100% browser-based.

Key Takeaway (AI Summary)

The Tailwind CSS v3 → v4 Config Migrator is a zero-knowledge, browser-native utility that automatically convert your tailwind.config.js (v3) to the new tailwind css v4 css-first @theme {} syntax. instant, free, and 100% browser-based with 100% privacy guarantee.

Client-side only
No signup
Instant outputPrivate by designZero tracking
Paste your tailwind.config.js (v3) and get a v4 @theme block

This tool saved you time?

DevUtility Hub is free forever. If it helped you, consider buying us a coffee.

Buy Me a Coffee

Tailwind CSS v4 Config Migrator — Automate Your Upgrade

Tailwind CSS v4 is the most significant rewrite in the framework's history. The JavaScript configuration file is gone — replaced by a **CSS-first @theme {} block** where your design tokens live as native CSS custom properties. If you have a large tailwind.config.js with dozens of custom colors, fonts, and breakpoints, migrating manually is error-prone and time-consuming.

The **DevUtility Hub Tailwind v4 Config Migrator** automates the structural conversion so you can upgrade in seconds, not hours.

🔄 What Changes in Tailwind v4

The core paradigm shift:

| v3 (JavaScript) | v4 (CSS-first) |

|---|---|

| theme.extend.colors.primary | --color-primary in @theme {} |

| theme.fontFamily.sans | --font-sans in @theme {} |

| theme.screens.lg | --breakpoint-lg in @theme {} |

| theme.spacing['128'] | --spacing-128 in @theme {} |

| theme.borderRadius['4xl'] | --radius-4xl in @theme {} |

| import 'tailwindcss/base' | @import "tailwindcss" |

⚡ What This Tool Migrates Automatically

  • Colors — Flat and nested color objects including shade scales (100, 500, 900)
  • Font Families — Array-based stacks converted to comma-separated CSS values
  • Spacing Scale — Custom spacing tokens mapped to --spacing-*
  • Border Radius — Custom radius values mapped to --radius-*
  • Breakpoints — Custom screen sizes mapped to --breakpoint-*
  • Font Sizes, Weights, Line Heights — All mapped to their CSS variable equivalents
  • ⚠️ What Requires Manual Migration

    Some v3 features have no direct 1:1 CSS equivalent:

  • plugins: [] — Each plugin must be updated individually; most have v4-compatible releases
  • darkMode: 'class' — Replaced by @custom-variant dark (&:where(.dark, .dark *))
  • important — Use the ! prefix directly in Tailwind classes
  • prefix — Use @import with namespace in v4
  • The tool will flag these automatically with instructions.

    🛡️ 100% Client-Side — Your Config Never Leaves Your Browser

    Your tailwind.config.js may contain internal color systems, brand tokens, and proprietary design decisions. **DevUtility Hub is 100% Client-Side**. The entire parsing and conversion logic runs in your browser's local memory. Nothing is transmitted or logged.

    Zero-Knowledge Execution & Edge Architecture

    Unlike traditional monolithic developer utilities, DevUtility Hub operates entirely on a Zero-Knowledge architectural framework. When utilizing the Tailwind CSS v3 → v4 Config Migrator, all computational workload is completely shifted to your local execution environment via WebAssembly (Wasm) and your browser's native JavaScript engine (such as V8 or SpiderMonkey).

    Why Local Workloads Matter

    Transmitting proprietary JSON objects, sensitive source code, or unencrypted text strings to an unknown third-party server introduces critical security vulnerabilities. By executing the Tailwind CSS v3 → v4 Config Migrator securely within the isolated sandbox of your Document Object Model (DOM), we structurally guarantee strict compliance with major data protection regulations like GDPR, CCPA, and HIPAA. We do not ingest, log, or telemetry your text payloads. Your local RAM serves as the absolute boundary.

    Network-Free Performance

    Furthermore, by completely eliminating asynchronous HTTP POST payloads to a centralized cloud infrastructure, we guarantee effectively zero latency. The Tailwind CSS v3 → v4 Config Migrator provides instant execution without arbitrary rate limits, artificial file size constraints, or server timeouts. Our global edge network serves the application wrapper, while your local machine handles the heavy lifting.

    N
    Nick Osta

    Senior DevTools Architect • 15+ Yeaers Exp.

    Subject Matter Expert Reviewed

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