IDNA

This plugin adds IDN support to WordPress, making it an IDNA application. An IDN is a domain name that contains non-ascii characters.
This plugin enables one to set the WordPress address (URL) to an IDN. (instead of the Punycode Representation)

Examples of an IDN:

• bücher.ch
• domæne.dk
• nörgler.com
• uddannelsesstøtte.dk
• müller.de
• räksmörgås.nu
• 画像.jp

“An IDNA-enabled application is able to convert between the internationalised
and ASCII representations of a domain name. It uses the ASCII form for DNS
lookups but can present the internationalised form to users who presumably
prefer to read and write domain names in non-ASCII scripts such as Arabic or
Hiragana. Applications that do not support IDNA will not be able to handle
domain names with non-ASCII characters, but will still be able to access such
domains if given the (usually rather cryptic) ASCII equivalent.” –
IDN entry at Wikipedia

In simple terms, this plugin allows one to set their blog url to an IDN.

If you are interested in seeing what the PUNYCODE version of your IDN is, here is an online conversion tool

As an example:

Frau Müller has a blog and wants to use the IDN, http://www.müller.de
Currently, she would have to set the WP blog url, (General Settings menu) to
the Punycode version: xn--mller-kva.de, (which is the ascii representation
of müller.de) this would allow users using a IDN aware web browser to access
the site using the desired url: http://www.müller.de
(and also of course, xn--mller-kva.de).

It is more convenient for Frau Müller to use the actual IDN
http://www.müller.de as the WP blog url setting (General Settings menu),
this plugin enables that functionality.

There are a few caveats with using this plugin, depending on what Browser, Operating
System and versions used, one can get unexpected results.

Firefox >= 3.*

Firefox supports IDN’s but maintains a ‘whitelist’ of ‘safe’ domains.
.com, .net, .eu are not white listed for safety reasons, so IDN’s on these
domains will display as Punycode. see bug:

There is an new (‘experimental’) Firefox add-on,
IDN Navbar, which
will enable all (whitelisted – Punycode) domains to display as IDN’s.
So, if using Firefox and this plugin you (and your visitors) may want to install that addon.

Internet Explorer >= 7.*

Depending on your language set up, site’s that contain non ‘native language’
characters will display as Punycode and not the IDN. More info
msdn blogs
msdn libs1
msdn libs2

Safari/Opera 10.* seem to display IDN’s for all domain’s fine. (untested)

Arbitrary section

WP plugins have a ‘stable tag’ requirement for distribution, however, at this
time, I consider this plugin to be Beta quality at best.

It is possible to lock your self out of the administrative section of your blog

NOTE make sure you are using an IDN capable web browser when enabling this plugin.
More

NOTE Unfortunely, Current Firefox versions display the Punycode version and
NOT the IDN. For more details, (and work around) see the ‘Other Notes’ Link
(Arbitrary section – readme.txt)

IE7/8, Safari, Opera10 all display the actual IDN, Firefox (and Chrome)
navigation bar’s display the IDN as Punycode. (i.e. www.xn--)

There are some security issues with multi-byte chars and phishing, so this is
Mozilla’s current approach, this may change in the future, as some folks are not
happy about it.

https://bugzilla.mozilla.org/show_bug.cgi?id=542562
another related, one: https://bugzilla.mozilla.org/show_bug.cgi?id=354592

Because this plugin effects how you access your site, installation is slightly more
involved than most plugins.

If you installing this plugin, I would recommend, if possible, that it is the
first thing you do on your blog, before you add any content, just in case
something goes wrong, this will minimize downtime.

NOTE If something goes wrong and you cant access the WP admin area after
changing your url, here are some instructions for
resetting your url

Please report any bugs you find to the author of this plugin