RTL Helper, by Reza Asadi, is a Firefox extension that fixes layout and rendering issues on sites lacking Right-to-Left language support. The app forces page direction, lets technical users inject custom CSS, and preserves site-specific settings so misaligned text and broken flows render correctly during testing. It also smart-detects elements to exclude from RTL and adapts its interface to dark mode. Web developers, localization specialists, and native RTL speakers gain fine-grained control for desktop and mobile QA.

How the app corrects RTL layout problems

The tool applies direction changes at page or element level and stores those preferences per domain, which supports repeatable verification across test sessions. Targeting specific blocks reduces unintended reflows in complex component trees. By adding style rules rather than rewriting HTML, visual adjustments are reversible and testers can confirm fixes without modifying source files, making it suitable for UI debugging and regression checks.

Which languages and browser environments it supports

The extension is designed for Persian, Arabic, Hebrew, Urdu, Kurdish, and Pashto, addressing common RTL scripts used in localization workflows. It runs on Firefox for desktop and Android and is also offered for Chrome and Edge variants that support extensions, relying on Manifest V3 compatibility. A keyboard shortcut lets testers toggle rendering quickly during live inspections and cross-language comparisons.

Developer workflow integration for targeted fixes

The app permits injection of custom CSS and font overrides to correct framework-specific layout bugs when upstream changes are impractical. Smart detection excludes URLs, emails, and numbers from forced RTL so machine-readable strings remain legible. Exporting saved preferences to JSON lets teams migrate configurations between environments or share a known-good test setup, which speeds repeated cross-device validation.

Performance, privacy, and mobile readiness

Designed to operate locally, the tool avoids external APIs, analytics, and data collection, which aligns with privacy-focused QA processes. The user interface adapts to light and dark themes and the touch-optimized controls are suited to Firefox on Android, enabling mobile verification. The key compatibility caveat is the requirement for modern browser support to access the full feature set.

A focused tool for technical testers and localizers

RTL Helper is a practical choice for developers and localization engineers who require repeatable, site-specific RTL verification across desktop and mobile. The extension rewards users who can author and tune styles for edge-case layouts; those expecting an immediate global switch may need a short adjustment period. Consider the browser compatibility requirement when planning cross-environment QA runs.