RegexRenamer

RegexRenamer is file renamer with only one way to rename: regular expressions. OK, there's adding number sequence, but it doesn't work (see cons). Usually only the most advanced users will be able to fully appreciate it. Expressions can be used both for renaming and filtering input files. The used implementation is one from Microsoft .NET 2.0, which is said to be compatible with PERL5. The help files explains that implementation. The interface is very clean, the tool is fast. It can integrate itself with Explorer context menu.

Pros:

1. Full Unicode support - while partial support can be found in almost every alternative, this one actually works. I tested it with only Cyrillic, only Chinese and mixed characters.
2. Very fast - it opened directory with 900 files in about 5 seconds, while Explorer does it in about 10 and other tools up to one minute
3. Fastness also applies to the live preview - it's virtually instant
4. Very regular expression debugging - if the expression is wrong, it shows tooltip with exact explaination. It's in my system locale, not application, so I guess it's taken directly from .NET. It has serious downside, tho. The tooltips are system-wide stay-on-top and can't be closed. One could either empty regular expression field or fix it.
5. Context menu with many snippets, skeletons etc., which can be used for creating expression or as a quick reference
6. Resulting names can be used to rename files in place, move or copy it
7. With my regular expression it was the only tool that recognized it
8. It highlights files to be renamed (i.e. match found) and rename conflicts. Status bar shows number of both, so it can be used as a quick check.
9. Manual path input - you can paste path and press enter. And no, it's not obvious. Many alternative tools requires browsing thought the directory tree without manual input ability.
10. Ignoring extension actually hide them from the list, which is very good for readability. It works well with double, triple, quad... with {2,} extensions - for files like IMG_1326.CR2.pp3, the hidden extension will produce IMG_1326.CR2. It's obvious, but it's good to know.

Cons:

1. Very limited history - user can't save expression (it would be nice to save profile and later load it), there are no rename logs and the only expressions history is combobox
2. There's no export/log option. The backup function doesn't save values but just copy files, so instead short list we have 2x disk space taken. If the export function would be available, it could be used as backup log or it could be saved to use it in other tool
3. The Microsoft/RegexRenamer implementation is rather poor. It lacks POSIX character classes (i.e. [:punct:], [:word:] etc.). It has only three modifiers (case insensitive, global and ignore unescaped spaces) and lacks ECMA compatibility, which is provided by .NET 2.0. There's no recursion ((?R)) support.
4. Inserting number sequence doesn't work. The ways of the application are unknown. There's no way to change order and it's quite weird. With image files it added numbers - IMG_13211, IMG_13002, IMG_13013, IMG_13224, IMG_15285. It looks totally random.
5. It doesn't obey font dpi settings from Windows. My Windows settings include bigger text, but most text in the application is still small. The short top-right menu obeys it, but the upper panel is too small, so the part of the menu is invisible. Also it uses some retro, anti-UX style where buttons looks like straight labels and they are bordered only on mouse hover. It took me some time to realize that top-right labels aren't labels, but buttons.

Cons are rather only in advanced use, but the point is that the tool is advanced by itself, so you may encounter it often. Still, even with serious cons, I think the tool does it job well. Most things are just missing, not broken. I give it 7 kielbasas out of 10.