Plugin provides toolbar (admin bar) menu to quickly switch between available themes.

Theme choice is individual for user, saved in cookies and doesn't affect current theme of the site.

Plugin is multisite-aware — it will only list themes allowed for site and save choice for each site separately.

Download plugin archive from releases section.

Or install in plugin directory via Composer:

composer create-project rarst/toolbar-theme-switcher --no-dev

You can reset via special URL parameter example.com?tts_reset or by clearing browser’s cookies for the site.

Filter tts_allowed_themes and unset unwanted themes.

Example code (removes Twenty Ten theme from the list):

add_filter( 'tts_allowed_themes', 'hide_twenty_ten' );

function hide_twenty_ten( $themes ) {

	unset( $themes['Twenty Ten'] );

	return $themes;
}

Users with switch_themes capability (administrators by default).

Filter tts_capability (capability name) or tts_can_switch_themes (boolean) to customize.

Filter tts_root_title to control what it says.

Plugin needs to build full list of available themes, which isn't typically needed on each page load and can be relatively slow with a lot of disk access.

When using Object Cache, caching theme data in WordPress can be enabled via:

add_filter( 'wp_cache_themes_persistently', '__return_true' );

Since it doesn't handle invalidation (will need to wait or flush cache when themes are added/removed), plugin isn't enabling it and leaves choice up to the user.