pseudo-localization

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Introduction

pseudo-localization helps developers test UI elements for localisation issues before real translations are available. It transforms text into a pseudo-language that simulates text overflow from longer translations, font rendering of larger glyphs, and right-to-left layouts.

pseudoLocalizeString converts strings, and PseudoLocalizeDom pseudo-localises the DOM and watches for changes in real time. Strategies include accented and bidi. A live demo applies it to Hamlet.

In the quality loop it finds hard-coded strings and layout breaks early.

The source code is at tryggvigy/pseudo-localization on GitHub under the MIT licence, with about 141 stars; the most recent commit was on 24 September 2026.

Features

1. Accented strategy: Longer, accented text.
2. Bidi strategy: Right-to-left simulation.
3. DOM mode: Live page transformation.
4. String API: pseudoLocalizeString.
5. Mutation observer: Real-time updates.
6. Framework-agnostic: Any web UI.

Pros

1. Zero translation cost: Tests before translators.
2. Free to use: Open source under the MIT licence, so the core tool costs nothing to use.
3. Actively maintained: The repository had commits as recent as 24 September 2026.

Cons

1. Small project: Few maintainers.
2. Web only: JavaScript environments.
3. Not real translation: Cannot catch grammar issues.

Usage and Links (Example)

import { pseudoLocalizeString } from 'pseudo-localization';
import { PseudoLocalizeDom } from 'pseudo-localization/dom';

pseudoLocalizeString('Save changes', { strategy: 'accented' });
const stop = new PseudoLocalizeDom().start();

Resources:

• pseudo-localization website

Pricing

pseudo-localization is free and open source under the MIT licence.

Recommended for?

1. Front-end teams preparing products for many languages.

Conclusion

pseudo-localization is a quick way to find i18n bugs early.

Run it in a dev build or visual tests.

On CheckOps, pseudo-localization is filed under the End-to-end & functional and Prototype & UX testing stages. Related tools listed here include i18n-tasks, Percy, Chromatic, Applitools, BackstopJS and Playwright. Which one fits best depends mostly on your stack, your team’s size and skills, and whether you prefer to run tools yourself or pay for a managed service. This page reflects the official website, documentation and repository as they stood on 11 November 2026.