Some of our customers had asked, they converted some ASCII files to UTF-8 without BOM but UTFCast Pro output the same contents as the source files to the output folder, the files were likely not converted. Please note this is not a bug. The files were converted, however, they have the same content after conversion. This is a normal behavior defined by the UTF-8 standard.
UTFCast Pro detects 30+ codepages, one of the codepages is ASCII. The ASCII codepage means every character in the text file is a pure ASCII character (or a US-ASCII character). A pure ASCII character is a character that its ASCII code is between 0 and 127. There are 128 pure ASCII characters in the UTF-8 character table.
A pure ASCII character will leave untouched after the UTF-8 conversion for backward compatibility, and if all of the characters in the input file are pure ASCII characters, after converting to UTF-8 without BOM, the output file will contain the same character sequence as the input file and the file content remains the same. This behavior is defined by the UTF-8 standard. Click here to read more details about UTF-8. If a file contains only pure ASCII characters, it will be marked as UTF-8/US-ASCII in UTFCast Pro.
Generally, there is no need to convert a pure ASCII file to UTF-8 without BOM, unless you need to normalize or change return type of the file. But if you are unsure whether a file is a pure ASCII file, or do not want to manually pick the pure ASCII files out of your folder, you can rely on UTFCast Pro and let it do the right job. UTFCast Pro does every conversion strictly according to Unicode standards. You can be assured of the conversion result.