Search service

The search service (toolkit/components/search/) manages the available search engines, the default engine selection, suggestions, and integration with the address bar.

Pieces

• SearchService.sys.mjs — registry and selection.
• SearchEngineSelector.sys.mjs — picks the default engine based on locale, region, and remote configuration.
• SearchEngine.sys.mjs — the data model.
• SearchSuggestionController.sys.mjs — fetches suggestions from the engine's suggest URL.

Data sources

• Built-in engines — bundled .js engines per locale.
• Remote Settings — Mozilla's CDN-distributed config (search-config-v2 collection) selects engines per region/locale.
• OpenSearch — sites can offer engines via <link rel="search">; users add them.
• WebExtensions — extensions can register engines via chrome_settings_overrides.search_provider in the manifest.

Region / locale logic

SearchEngineSelector consults remote-settings-derived JSON to choose engines for the user's (region, locale) pair — including legal holdout markets (e.g., Russia, Kazakhstan) and partner deals.

Related

• Toolkit components
• Localization