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 that this is not a bug. The files were correctly converted. However, they happen to have the same content after conversion. It 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) whose ASCII code is between 0 and 127. There are 128 pure ASCII characters in the UTF-8 character table.
A pure ASCII character will be untouched after the UTF-8 conversion for backward compatibility. 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. The UTF-8 standard defines this behavior. Click here to read more details about UTF-8. If a file contains only pure ASCII characters, UTFCast Pro will mark it as UTF-8/US-ASCII.
Generally, there is no need to convert a pure ASCII file to UTF-8 without BOM unless you need to normalize or change the return type of the file. But if you are unsure whether a file is a pure ASCII file or do not want to pick the pure ASCII files out of your folder manually, you can rely on UTFCast Pro and let it do the right job. UTFCast Pro does every conversion strictly according to Unicode standards.