Supercharge Your i18next Workflow with a Real-Time, Persistent Cache

This content originally appeared on DEV Community and was authored by Adriano Raiano

I originally published this guide on the Vaultrice blog and wanted to share it with the Dev.to community to get your thoughts and feedback.

At Vaultrice, our goal is to eliminate backend complexity for real-time applications. Today, we're excited to take that mission a step further by releasing the new i18next-vaultrice-backend, a powerful backend plugin for the amazing i18next localization framework.

While you can use it as a primary, serverless backend for your translations, its true power lies in its ability to act as a persistent, cross-device, real-time cache.

This isn't just another localStorage cache. Imagine a user loading your application on their desktop, which populates the translation cache. When they later open the app on their phone, the cache is already warm—no need to re-fetch anything. Or imagine fixing a typo in your translation management system and having it update instantly on every live user's screen.

That's what this plugin enables. Let's dive in.

The Core Use Case: A Smarter Caching Layer

The most powerful way to use this plugin is with i18next-chained-backend. This setup creates a "cache-first, then fetch" strategy:

1. i18next first asks i18next-vaultrice-backend for the translations.
2. If the translations are in the Vaultrice cache (a cache hit), they are returned instantly.
3. If not (a cache miss), the chain continues to the fallback backend (e.g., i18next-http-backend), which fetches the translations from your server or CDN.
4. Once fetched, the chained backend automatically calls save() on our plugin, populating the Vaultrice cache for the next page load, the next device, or the next user.

Here’s how you wire it up:

import i18next from 'i18next';
import ChainedBackend from 'i18next-chained-backend';
import VaultriceBackend from 'i18next-vaultrice-backend'; // Primary cache
import HttpBackend from 'i18next-http-backend';           // Fallback loader

i18next
  .use(ChainedBackend)
  .init({
    backend: {
      backends: [
        VaultriceBackend,
        HttpBackend
      ],
      backendOptions: [
        {
          credentials: { /* your vaultrice credentials */ },
          class: 'translations-v1.1',
          // id: 'eu-i18n-resources' or similar if needed
        },
        {
          loadPath: '/locales/{{lng}}/{{ns}}.json'
        }
      ]
    }
  });

`

The id Option — And Why First Request Placement Matters

The id option determines which Vaultrice Durable Object your translations live in. This is critical because the first request to a given id decides where that Durable Object is physically hosted. After creation, that object will have its “home region,” and all future writes go there.

That means your id is not just a name — it’s a placement strategy.

Best practice

• Use global IDs for public, static translations.
• Use regional IDs when you must comply with residency rules or want to create some regional cache clusters to lower the latency — and implement logic to map users to the right region.
• Use per-user only when you need strict isolation (e.g., each user’s private translations), and accept lower cache efficiency.

How to Decide Region or Jurisdiction for an id

If you want to pin data to a region (e.g., eu-*):

• Best: Detect location server-side using IP geolocation or CDN-provided headers.
• Alternative: Ask users to select a region in their profile and use that to pick the id.
• Browser-only (last resort): Use hints like navigator.language, Intl.DateTimeFormat().resolvedOptions().timeZone, or the Geolocation API (with user consent).

For legal residency requirements, don’t rely on client hints alone — they can be spoofed or denied.

Beyond Basic Caching — Advanced Usage

Because i18next-vaultrice-backend is built on the full @vaultrice/sdk, you have more than just a key/value cache.

End-to-End Encryption

If translations are sensitive, add a passphrase to encrypt client-side before sending:

javascript
{
credentials: { /* ... */ },
passphrase: 'a-strong-secret',
class: 'translations-v1.2-confidential'
}


The data stays encrypted in Vaultrice, decrypted only on the client.

Live Reloading

Set reloadInterval to poll Vaultrice periodically:

javascript
{
credentials: { /* ... */ },
reloadInterval: 60000 // check every 60s
}


Paired with an admin dashboard that writes to Vaultrice, this means live apps update automatically — no refresh needed.

Customizing the Storage Layer

You can use the onNonLocalStorageCreated callback to access or customize the underlying Vaultrice NonLocalStorage instance.

This is useful if you want to manipulate something or for tasks like manually updating the access token.
You can find more information about this authentication approach here.

Example:
javascript
const backendOptions = {
credentials: {
projectId: 'my-project-id',
accessToken: 'my-first-shord-lived-token'
},
onNonLocalStorageCreated: (nls) => {
nls.onAccessTokenExpiring(() => {
// get new access token from your backend...
nls.useAccessToken(newAccessToken);
});
}
};


But the more convenient way is to just inject the getAccessToken function:

Example:
javascript
const backendOptions = {
credentials: {
projectId: 'my-project-id',
getAccessToken: async () => await fetchNewAccessToken() // get new access token from your backend...
}
};


Standalone Backend Mode

You can skip chaining and use Vaultrice as your only backend:

javascript
i18next.use(VaultriceBackend).init({
backend: {
credentials: { /* ... */ },
id: 'shared-i18n-resources',
class: 'translations-v1.1'
}
});


Best for serverless apps or when translations are managed directly in Vaultrice.

Multi-load Efficiency

The backend implements readMulti to fetch multiple language/namespace combos in one call. This is ideal for SSR or preloading:

`javascript
import i18next from 'i18next';
import VaultriceBackend from 'i18next-vaultrice-backend';
import MultiLoadBackendAdapter from 'i18next-multiload-backend-adapter';

i18next.use(MultiLoadBackendAdapter).init({
lng: 'en',
fallbackLng: 'en',
preload: ['en', 'de'],
ns: ['ns1', 'ns2'],
defaultNS: 'ns1',
backend: {
backend: VaultriceBackend,
backendOption: {
credentials: {/* */}
}
}
});
`

Using It on Client, Server, and Serverless

i18next-vaultrice-backend works in:

• Browsers — great for cross-device caching.
• Mobile apps — same API, persistent cache across sessions/devices.
• Node.js servers — SSR with warm caches.
• Serverless functions — low-latency translation fetches without bundling files.

Wrapping Up

The i18next-vaultrice-backend isn’t just a backend — it’s a new caching layer for translations:

• Persistent across sessions and devices.
• Real-time updatable.
• Flexible enough for global, regional, or per-user strategies.
• Usable in browsers, mobile, Node.js, and serverless.

Think about your id strategy early — it decides where your cache lives and how fast it will be for your users. Pair that with a chained setup, and you’ve got a low-latency, always-fresh translation layer for your entire stack.

Conclusion

The i18next-vaultrice-backend is more than just another backend; it's a new way to think about your localization workflow. By leveraging a persistent, global, and real-time platform, you can build faster, more dynamic, and more easily managed international applications.

Give it a try today and supercharge your i18next setup.

This content originally appeared on DEV Community and was authored by Adriano Raiano

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Adriano Raiano | Sciencx (2025-08-26T12:02:28+00:00) Supercharge Your i18next Workflow with a Real-Time, Persistent Cache. Retrieved from https://www.scien.cx/2025/08/26/supercharge-your-i18next-workflow-with-a-real-time-persistent-cache/

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