Machine-Dependent Character Checker
Scans your text for machine-dependent characters (also called environment-dependent characters) such as circled numbers (①②③), Roman numerals (ⅠⅡⅢ), and ligatures like ㈱ ㍉ ㍻. Use it before sending an email or newsletter, or filling in a web form, to catch characters that might turn into mojibake on the recipient's device. Need to convert between full-width and half-width characters instead? Try the Full-width / Half-width Converter.
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Notes
- This tool checks for well-known machine-dependent characters (NEC special characters, NEC-selected IBM extension characters, and similar). It does not cover every environment-dependent character that exists.
- The suggested replacements are general-purpose defaults. Depending on context (for example, wanting to keep "㍿" as part of a company name), a different replacement may be more appropriate — always review the replaced text before using it.
- IBM extension variants such as "髙" and "﨑" are sometimes used intentionally in personal or place names. A mechanical replacement may not always be appropriate for these.
Glossary
Machine-dependent characters (kishu-izon moji)
Characters such as circled numbers (①②③), Roman numerals (ⅠⅡⅢ), and ligatures like ㈱ ㍉ ㍻ that were added outside the standard JIS character set by specific PC vendors. They may look fine on the sender's device but turn into different characters or "mojibake" (garbled text) on another device, OS, or mail client.
Mojibake (garbled text)
Text that displays as the wrong characters or as "�" placeholders because of a mismatch in character encoding interpretation. Many machine-dependent characters live in vendor-specific extension areas of encodings such as Shift_JIS, which makes them especially prone to this problem.
Shift_JIS
A character encoding once widely used on Japanese Windows systems. In addition to standard JIS kanji, PC vendors added their own extension areas (NEC special characters, IBM extension characters, and so on), which is the main source of machine-dependent characters.
FAQ
What are platform-dependent characters and why are they a problem?
They are characters such as circled numbers (①), Roman numerals (Ⅰ) and ㈱ that may not display in every environment. In emails or web forms they can turn into "?" on the recipient's system.
Does it detect every environment-dependent character?
No. It covers representative sets such as NEC special characters and NEC-selected IBM extensions, not everything. Check important documents separately.
Should variant kanji such as 髙 be replaced too?
These can be the correct spelling in personal or place names, so blind replacement can be wrong. Treat suggestions as a guide and review the result.
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