This plugin hasn’t been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.

UNFC Nörmalize


This is a souped-up version of the Normalizer plugin by Torsten Landsiedel.

It adds WP filters to normalize UTF-8 data coming into the system to the de facto web standard Normalization Form C. The Unicode Consortium report is at Unicode Normalization Forms.


For best performance install (if possible) the PHP Internationalization extension Intl, which includes the PHP class Normalizer.

However the plugin works without the PHP Intl extension being installed, as it uses (a modified version of) the Symfony Normalizer polyfill.

Also text pasted into (most) inputs is normalized immediately using the JavaScript normalize() method. For browsers without normalization support, the unorm polyfill is used.


For further info, see the WP Trac ticket #30130 Normalize characters with combining marks to precomposed characters and this Make WP Core comment.

The plugin also works around the Safari-specific issues raised by the WP Trac ticket #22363 Accents in attachment filenames should be sanitized.


For existing data, the plugin includes an administration tool to scan and normalize the database. Important: before using this tool to normalize, please backup your database. This is especially important if your database contains non-normalized serialized data, as this plugin uses the same suck-and-see technique as interconnect/it’s Database Search and Replace Script in PHP to deal with serialized data, and is fallible.


A google-cheating schoolboy French translation is supplied.

The plugin should run on PHP 5.2.17 to 7.1, and on WP 3.9.13 to 4.7.1.

The project is on github.


  • Before and after: pasting non-normalized text into a post’s title and content.
  • Before: uploading a file on macOS with Firefox and then viewing with Safari (broken in Safari).
  • After: uploading a file on macOS with Firefox and then viewing with Safari (whee it works).
  • Front page of the database scan administration tool.


Install in the standard way via the ‘Plugins’ menu in WordPress and then activate. No further action is needed.


How can I normalize extra stuff?

You can add normalization to anything that passes its content through a filter. The canonical way is to use the unfc_extra_filters filter which returns an array of filter names – for instance, in your theme’s functions.php file, add:

function mytheme_unfc_extra_filters( $extra_filters ) {
    $extra_filters[] = 'myfilter';
    return $extra_filters;
add_filter( 'unfc_extra_filters', 'mytheme_unfc_extra_filters' );

Note that the unfc_extra_filters filter is only called in the administration backend. You can also add a filter directly, to be called in the frontend or backend, by referencing the global PHP variable unfc_normalize, but you should ensure that the Normalizer polyfill is loaded if you don’t have the PHP Intl extension installed:

global $unfc_normalize;
if ( $unfc_normalize ) {
    if ( ! function_exists( 'normalizer_is_normalized' ) ) { // If the "Intl" extension is not installed...
        $unfc_normalize->load_unfc_normalizer_class(); // ...load the polyfill.
    add_filter( 'myfilter', array( $unfc_normalize, 'normalize' ), 6 /* Or whatever priority you choose */ );
Does it have a tool to normalize the filenames of files uploaded prior to its enabling?

No, it doesn’t. Alas, such files would have to re-uploaded. However if (enough – or more like any) interest were expressed…


4 marca, 2020
Thank you very much. I am building a site to upload and search large amounts of PDF documents in Japanese. Some of the characters copy and paste from the PDF title, PDF content, file name, etc. to the WordPress post title did not match the search due to NFD. *Copy and paste is done on Windows. *Copying and pasting from a Mac file name or folder name always results in NFD. It’s working with WordPress 5.3.2. Thanks to this plugin, the NFD title problem has been solved. We hope that you can continue the maintenance. I want to donation too. The page I referred to in this issue. Thanks and Regards, yumsun
21 decembra, 2018
no update since 3 years. but working with WP 5.0.2. 20 Multisites need to get scanned and normalised singlewise. But still better then other solutions! Made my day!
Read all 2 reviews

Contributors & Developers

“UNFC Nörmalize” is open source software. The following people have contributed to this plugin.


Translate “UNFC Nörmalize” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.



  • Require explicit define of UNFC_DEBUG. Move load of debug file to ‘init’.
  • Safari submit workaround.
  • WP 4.7.1 compatible.


  • Do load of normalizer in slugs list constructor not items list. Fixes slugs listing crash when Intl extension not installed.
  • Ignore case when checking charset (UNFC_Normalize::is_blog_utf8()).
  • WP coding standards (yoda style in unfc_utf8_4range()).
  • Add screenshots.
  • Some extra unittests.
  • WP 4.7.0 compatible.


  • Add _wp_old_slug on normalizing slugs.
  • Escape title in screen reader label in db check.


  • For PHP 5 performance do preliminary preg_match on isNormalized.
  • Improve comments in Normalizer.php, tabs -> 4 spaces, UNFC_REGEX_IS_INVALID_UTF8_XXX invert & rename.
  • Fix untested admin notice and adjust tests. Fix some test bleed ($wp_scripts).


  • Move all .php files bar main to includes subdir. Remove unused ajax.
  • Fix single-byte trie. Move regex alts to tools/functions.php.
  • Fix untested admin notice. Adjust tests for untested admin_notice change. Fix some test bleed ($wp_scripts).
  • WP 4.6 compatible.


  • First release for repository.
  • Add assets.
  • Include “class-unfc-list_table.php” in .pot file (for forward/backward compat).
  • Remove unused variable in UNFC_DB_Check_Slugs_List_Table.


  • Initial release.


  • Fix bad serialized data corruption on db check.
  • Fix text domain tag.


  • Initial version after renaming from tl-normalize.