Locize vs. SimpleLocalize:i18next-Native vs. Generic TMS

Both tools support CDN delivery, an in-context editor, and AI translation. The real difference is how deeply each one understands i18next, and how much manual wiring you need to do to get there.

What "i18next support" actually means

SimpleLocalize is a well-built, general-purpose TMS that works with many frameworks including i18next. Locize is built by the creators of i18next, specifically as the managed backend for it. That difference shows up most clearly in three places.

1. The backend plugin

SimpleLocalize

Uses the generic i18next-http-backend plugin. You configure a CDN URL manually. There is no first-party plugin that understands Locize-style project IDs, API keys, or namespace structure.

backend: {
  loadPath: `${cdnBaseUrl}/${token}/${env}/{{lng}}`
}

Locize

Has a dedicated i18next-locize-backend plugin that is maintained by the same team as i18next. It handles project auth, namespace routing, version pinning, and the saveMissing create function natively, with no custom code.

backend: {
  projectId: '[PROJECT_ID]',
  apiKey: '[API_KEY]',  // only when using saveMissing feature or similar
}

2. The saveMissing workflow

SimpleLocalize

Supports saveMissing, but requires you to implement a custom missingKeyHandler that batches keys and flushes them to the API on a timer interval (recommended: 30 seconds). This is functional but requires manual setup and carries rate-limiting considerations.

Locize

The i18next-locize-backend implements the create function natively. Set saveMissing: true in your i18next config and new keys appear in Locize automatically: no custom handler, no timer, no batching logic to maintain. Combined with the automatic translation workflow, new keys can be AI-translated immediately.

3. Branches vs. Environments

SimpleLocalize

Offers environments (latest, production, custom). These are delivery namespaces, so you promote translations from latest to production when ready. There is no concept of a separate branch that mirrors a Git feature branch, where you can develop translations in isolation and then merge.

Locize

Offers proper branches that mirror Git branches. You can create a feature branch for a specific release, develop translations there independently, and merge back to main, preserving the same mental model your developers already use.

4. Multi-tenant SaaS support

SimpleLocalize

No native multi-tenant namespace concept. SaaS teams managing per-client translation overrides would need to use separate projects or custom workarounds.

Locize

First-class tenant support. Each tenant gets its own namespace overrides served from the same CDN. Built specifically for SaaS products that need per-customer localization.

Where both tools are comparable

SimpleLocalize is a genuinely capable tool. Before evaluating, you should know what it does well:

—CDN delivery (no redeploy needed)

—In-context editor

—AI translation with BYOK

—Review workflow and comments

—Translation memory

—Glossary

—Figma integration

—GitHub Actions / CI integration

—Webhooks and REST API

—Staging / production environments

—Free plan available

—Public transparent pricing

Side-by-side

Feature	SimpleLocalize	Locize
Built by the i18next creators	✗	✓
Dedicated i18next-locize-backend plugin	✗	✓
saveMissing native (zero custom code)	✗	✓
saveMissing supported (custom implementation)	✓	✓
CDN delivery (no redeploy needed)	✓	✓
In-context editor	✓	✓
Git-style branches (merge, develop in isolation)	✗	✓
Staging / production environments	✓	✓
Multi-tenant namespace support	✗	✓
AI translation with BYOK	✓	✓
Automatic translation on saveMissing	✗	✓
Translation memory	✓	✓
Glossary	✓	✓
Review workflow	✓	✓
Figma integration	✓	✓
Free plan	✓	✓
Public pricing	✓	✓

Based on publicly available documentation as of March 2026. Features change, so verify before purchasing.

Consider SimpleLocalize if…

Price is the primary constraint and the lower base cost matters
Your localization workflow is primarily file-based (export → translate → import)
You do not need git-style branches or multi-tenant namespaces

Choose Locize if…

You are using i18next, react-i18next, next-i18next, or any i18next-compatible library
You want saveMissing to work with zero custom code
Your release workflow uses Git branches and you want your translations to match
You are building a SaaS product and need per-tenant translation overrides
You want your TMS subscription to directly support i18next open-source development

AI Translation Infrastructure

SimpleLocalize offers basic auto-translation. Locize provides a full AI pipeline: BYOK for OpenAI, Gemini, and Mistral, plus a built-in AI service. Your styleguide, glossary, and translation memory feed into every AI prompt, so translations stay consistent as your project grows.

The Locize MCP server connects AI coding assistants directly to your translation projects, so you can manage translations from Claude, Cursor, or VS Code without switching context. Why not just use AI? →

SimpleLocalize migration guide Start free trial

Frequently asked questions

What is the difference between Locize and SimpleLocalize?

Both offer CDN delivery, an in-context editor, and AI translation, so the difference is depth of i18next integration. SimpleLocalize is a capable general-purpose TMS used with the generic i18next-http-backend plugin and a manually configured CDN URL. Locize is built by the creators of i18next and ships a dedicated i18next-locize-backend plugin that handles project auth, namespace routing, and version pinning natively.

How does saveMissing differ between Locize and SimpleLocalize?

SimpleLocalize supports saveMissing, but you implement a custom missingKeyHandler that batches keys and flushes them on a timer, which works but is code you own and carries rate-limiting considerations. In Locize, i18next-locize-backend implements the create function natively: set saveMissing to true and new keys appear automatically, with no handler, timer, or batching logic. Combined with automatic translation, new keys can be AI-translated immediately.

Does SimpleLocalize support branches?

SimpleLocalize offers environments such as latest and production, which are delivery namespaces you promote between. There is no separate branch mirroring a Git feature branch where translations can be developed in isolation and then merged. Locize offers git-style branches that match that mental model directly, alongside first-class tenant support for per-customer overrides.

When should I choose SimpleLocalize over Locize?

SimpleLocalize is a genuinely capable tool and a sensible pick if price is your primary constraint and its lower base cost matters, if your workflow is mainly file-based export and import, and if you do not need git-style branches or multi-tenant namespaces. It also covers review workflow, comments, CI integration, and transparent public pricing.

Can I migrate from SimpleLocalize to Locize?

Yes. Both support standard formats such as JSON and XLIFF, and the Locize CLI and Import API can ingest files exported from SimpleLocalize. Since both work with i18next, the runtime change is typically replacing i18next-http-backend with i18next-locize-backend and removing your custom missing-key handler. A step-by-step SimpleLocalize migration guide is in the docs.