Comparison
Paraglide's compiler approach enables optimizations that are not possible with runtime libraries. Below is a comparison of Paraglide JS with other popular i18n libraries.
If you are looking for a benchmark, check out the interactive benchmark.
[!NOTE] Please open a pull request if the comparison is outdated, incorrect, or can be improved.
Basic Features
| Feature | Paraglide JS | i18next | React-Intl/FormatJS |
|---|---|---|---|
| Architecture | 🏗️ Compiler | 🏃 Runtime | 🏃 Runtime |
| Tree-shaking | ✅ Yes | ❌ No | ❌ No |
| i18n Bundle Size | ✅ Up to 70% smaller via tree-shaking | ⚠️ Ships all messages | ⚠️ Ships all messages |
| Type Safety | ✅ Yes | 🟠 Via workarounds (opens in a new tab) | ❌ No |
| IDE Autocomplete | ✅ Full (keys + parameters) | 🟠 Keys only, requires setup | ❌ No |
| Pluralization | ✅ Yes (opens in a new tab) | ✅ Yes (opens in a new tab) | ✅ Yes (opens in a new tab) |
| Framework agnostic (React, Svelte, Vue, ...) | ✅ Yes | 🟠 Wrappers needed (opens in a new tab) | 🟠 Wrappers needed (opens in a new tab) |
| Metaframework agnostic (NextJS, SvelteKit, Astro, ...) | ✅ Yes | 🟠 Wrappers needed (opens in a new tab) | ❌ Only supports plain JS or React (source (opens in a new tab)) |
Advanced Features
| Feature | Paraglide JS | i18next | React-Intl/FormatJS |
|---|---|---|---|
| Configurable strategies ℹ️ (opens in a new tab) | ✅ Yes (opens in a new tab) | 🟠 Via plugins (opens in a new tab) | ❌ No |
| Localized (i18n) routing | ✅ Yes (opens in a new tab) | ❌ No | ❌ No |
| SSR/SSG support | ✅ Built-in (opens in a new tab) with request isolation via AsyncLocalStorage | 🟠 Via middleware (opens in a new tab), risk of locale bleeding | 🟠 Limited, React only |
| Variants ℹ️ (opens in a new tab) | ✅ Yes (opens in a new tab) | ❌ No | ❌ No |
| Multi-tenancy ℹ️ (opens in a new tab) | ✅ Yes (opens in a new tab) | ❌ No | ❌ No |
| Message syntax agnostic ℹ️ (opens in a new tab) | ✅ Via inlang plugins (opens in a new tab) | ✅ Via different backends (opens in a new tab) | ❌ Only ICU |
| Lazy locale loading ℹ️ | 🟠 Experimental (opens in a new tab) | ✅ HTTP backend (opens in a new tab) | ❌ No |
| Component interpolation | ✅ Yes (opens in a new tab) | 🟠 Only for React (opens in a new tab) | 🟠 Only for React (opens in a new tab) |
Paraglide supports ICU MessageFormat 1 syntax through the inlang-icu-messageformat-1 plugin (opens in a new tab).
Lazy locale loading
Paraglide compiles messages into functions that contain all locales. Lazy locale loading instead fetches only the current locale's messages on-demand.
When does this matter?
Under ~20 locales, tree-shaking unused messages outweighs the cost of bundling all locales per message—Paraglide remains more efficient. Beyond ~20 locales, lazy loading may become beneficial depending on your app's message usage patterns.
Paraglide has an experimental locale splitting option (opens in a new tab) for apps that need lazy locale loading.
[!NOTE] There is no locale limit in Paraglide. The library works fine with any number of locales. Lazy loading is an optimization, not a requirement.
Further Reading
- Why I Replaced i18next with Paraglide JS (opens in a new tab) — A developer's experience reducing bundle size from 40KB to 2KB
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