A mechanism is provided for automatic determining of file transfer mode. A locale or an operating system of a client in a file transfer is determined. At least part of a transfer file is downloaded in a first text format to obtain first resulting bytes. The first resulting bytes are analyzed to determine whether the first resulting bytes match a character set of the locale or the operating system of the client above a first predetermined threshold. A determination is made as to whether the first text format should be used for downloading the transfer file based on whether the first resulting bytes match the character set of the locale or the operating system of the client above the first predetermined threshold. Responsive to the first resulting bytes matching above the first predetermined threshold, the transfer file is downloaded in the identified first text format.