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Domain hacks with unusual Unicode characters (2018)

Unicode contains a range of symbols which don't get much use. For example, there are separate symbols for TradeMark - ™, Service Mark - ℠, and Prescriptions - ℞.

Nestling among the "Letterlike Symbols" are two curious entries. Both of these are single characters:

What's interesting is both .tel and .no are Top-Level-Domains (TLD) on the Domain Name System (DNS).

So my contact site - https://edent.tel/ - can be written as - https://edent.℡/

And the Norwegian domain name registry NORID can be accessed at https://www.norid.№/

Copy and paste those links - they work in any browser!

Is this limited to TLDs?

No! This works ANYWHERE in a domain name. Copy and paste these examples:

There are a whole bunch more miscellaneous characters you can use:

How does this work?

Magic! Which is to say, I think it is the browser doing the conversion. DNS Servers don't successfully reply to queries about .℡ domains.

The browser sees the .℡ and then follows the IDNA2008 process listed in RFC5895 to normalise it:

map characters to the "Simple_Lowercase_Mapping" property (the fourteenth column) in <http://www.unicode.org/Public/UNIDATA/UnicodeData.txt>, if any.

The ℡ entry is:

2121;TELEPHONE SIGN;So;0;ON;<compat> 0054 0045 004C;;;;N;T E L SYMBOL;;;;

U+0054 is T, U+0045 is E, U+004C is L.

You can test this in Python using:

python -c 'import sys;print sys.argv[1].decode("utf-8").encode("idna")' "℡"

Does this work?

Yes! I asked people on Twitter whether they could access my website using a .℡ - and it appeared to work on every modern browser and operating system.

It even works on command line tools like wget and curl.

It does fail in some circumstances:

What are the limitations?

Two main ones:

Copied Bash to 📋 
 Bashdig edent.℡

; <<>> DiG 9.10.6 <<>> edent.℡
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 55282

Is this useful?

Obviously yes. This may be the most important discovery of the decade. You get cool looking URls and get to save a couple of characters on specific domains, at the minor expense of working inconsistently.

It could also be used for evading URl filters.

Every modern browser supports these "fancy" domain names - but most websites won't automatically link to them. So sharing on Facebook doesn't work.

Where can it be used?

Here are the single characters which can be normalised down to a valid TLD. They're mostly country codes, but there are a few interesting exceptions:

If you can find any more, please stick a comment in the box below.

You can always reach this blog post at:

https://🅂𝖍𝐤ₛᵖ𝒓.ⓜ𝕠𝒃𝓲/🆆🆃🅵/