Homoglyph characters are characters that look the same or similar on the screen and in print, but whose meaning and pronounciation are typically dissimilar.
A well-known example are the Latin capital letter O and the digit 0. A less well known example is the Latin capital letter H, the Greek capital letter letter Eta Η (U+0397) and the Cyrillic capital letter En Н (U+041D)
This site is intended as a reference tool on Unicode homoglyph characters and a tool for webmasters and programmers who want to avail themselves of them
You need to be aware of the possibility of homoglyph characters because they can be used maliciously in domain names and URLs to deceive Web users (see Unicode Technical Report #36 by the Unicode Consortium)
There are also useful and arguably legitimate uses for homoglyphs, in "security by obscurity" measures. For example, someone might want to state their name on a Web page that is indexed by search engines, but for privacy reasons not want for the page to be found by a web search for the name. Sometimes in these cases a bitmap graphic with the name is used. Use of homoglyphs from other alphabets would be a more lightweight solution (in this case the newly written name is a homograph of the actual name.) - but the reader of the web page in question would need to have the requisite font installed. For example, the Greek ο (omicron) is likely to be available on even perfectly monoglot users' computers, so if I did not want for this page to be found in a search for my name, I'd replace the o in my name with an omicron.
The "Fullwidth Latin" character range may not be the best choice for this use (avoiding certain words being indexed in search engines) because these characters have the same meaning as the normal Latin characters (the fullwidth characters were defined for Latin-alphabet texts in Chinese/Japanese/Korean (CJK) computing), so smart search engines might normalize these characters to the normal Latin ones.
How to use this site: You can select which character ranges to display and which to exclude by clicking the requisite checkboxes. If you then enter a text in the input box at the top, this site returns a text where the Latin characters are replaced by homoglyphs from the non-excluded character ranges (if there is more than one choice of homoglyph character, this site chooses randomly, i.e. if you click the button again you may get a different homoglyph rendering).
You can also print out a table with columns selected by you - there is an option for a printer-friendly display.
Limitations of this site:Your operating system and browser must support Unicode and UTF-8 to display this site, and the fonts on your computer must support display of the respective characters. You will very likely see replacment characters, a square or possibly a question mark, for characters that your computer does not display, particularly for not widely supported scripts like e.g. Cherokee. This is a client-side issue not a server-side one.
This site also focuses on homoglyphs of Latin characters. There are also e.g. a wide range of homoglyphs between the Cyrillic, Greek and Coptic alphabets.
Known bug: When viewed with Firefox, the browser sometimes does not display the thin black borders between columns of the character table, for some rows. This looks like an issue with the rendering engine that Firefox uses; the display issue is usually fixed by toggling the "printer-friendly display" setting.
The Unicode™ Standard is © Unicode, Inc.
See also my other sites Books by ISBN and The Aubrey/Maturin series by Patrick O'Brian, in reading order