Renominator Overview

Note: a new version was released on 5 June 2016; see the Release History below for more information.

Renominator is a powerful yet easy-to-use file renaming app for Mac OS X. All of its options are at your fingertips and you don't have to construct a large sequence of steps before seeing the result. Perform only one action or save several of your favourite actions as a profile for instant replay later. Renominator also uses conflict detection to prevent files from being renamed if any action would create duplicate file names; to continue anyway, simply deselect the offending file(s) shown in red in the preview column.

  • Folders - Click the Open button on the toolbar to open a folder and start using Renominator (it will be reopened the next time you start the app).
  • Toolbar - Various global options are available through the Toolbar at the top of the window. Click the Preview button to see changes to your file names instantly when you specify each action.
  • Profiles - Your favourite sets of Actions can be saved and reused again through the Profiles list on the Toolbar.
  • Files - The central area of the window shows the Files in the selected Folder.
  • Actions - Powerful options for renaming files all are at your fingertips in the Actions pane. The order in which Actions are applied to each filename can be changed to suit your needs using the up and down arrows at the top of each action. The order is reinstated when you load a saved Profile.
Renominator Window

Search and Replace

The most common task people perform when cleaning up file names is to search for certain words and replace them with others.

Enter the text you wish to remove in the Search box, and optionally tick the box if you want to match case, then enter the new text in the Replace box (or leave it empty if you simply want to remove the Search text):

Search and Replace - options

If the auto-preview button on the toolbar is clicked, a preview of the changes appears instantly (if not, click the Preview button at the top of the Actions pane for a one-off preview of your changes):

Search and Replace - preview

Files which are unaffected by Search and Replace appear in light-grey text. If the result of an action would cause a file name conflict, both of the offending files are highlighted red in the preview column, and renaming is prevented unless you amend the action or you deselect one or both files:

Search and Replace - file name conflicts

If you wish to search for and replace multiple pieces of text (and perhaps save them all for reuse later), enter a character in the Multiple separator box, then type as many pieces of text each separated by that character. The first piece of text before the separator in the Search box is replaced with the first piece in the Replace box, and so on.

Format Filename

Sometimes your filenames are around the wrong way, and you want to move words at the beginning to the end or vice versa. Format Filenames allows you quickly and easily to rearrange words to suit the desired format. There are two ways to specify the format (or pattern): a simple shorthand and using regular expressions.

Simple Formats

Not everybody has the time to learn regular expressions, so Renominator allows you to enter simple tokens to indicate chunks of text in a filename. Consider the following Format Filename action:

Format Filename - options

The following pattern in the Old box describes the filenames as they are currently -i.e., a chunk of text, followed by a hyphen with spaces either side, followed by another chunk of text:

$1 - $2

To swap these two parts of the filenames around, use the following format in the New box:

$2 - $1

This will match any files with a hyphen in the middle, and swap the other two parts around. The other two files in the picture below are not affected because neither contains a hyphen (and therefore do not match the format):

Format Filename - preview

You can enter as many tokens as you like in the Old box, just as long as they are in numerical order. You may omit any of these tokens in the New box if you wish to discard a matched chunk of text in the new filenames.

Regular Expressions

When simple formats won't do the job, you can unleash the power of regular expressions. The following expression in the Old box is equivalent to the simple shorthand above: "$1 - $2".

Format Filename - regular expression

A dot followed by an asterisk matches any character any number of times (or even nothing). Putting this expression in parentheses creates a group reference, which allows you to reuse any matching text in the New box. The expression in the first set of parentheses becomes $1, the second $2, and so on.

Consider this more advanced example:

(.*) (\d{2})$
Format Filename - advanced regular expression

The dot matches any character, and the asterisk tells it to match zero or more times. Then follows a space, and a group reference which expects to find exactly two numbers. The dollar sign at the end is an end-of-line anchor, which tells the regular expression to look for this pattern only at the end of the filename. The backslash followed by a lower-case "d" is shorthand for [0-9] which matches any digit. The number 2 inside curly braces says that you only want to match two digits; if you want to match two or three digits, you'd type {2,3}.

Format Filename - regular expression preview

In the picture above you can see that the action affected only two files which end with a space and two digits. Without the dollar sign at the end of the regular expression, Homer Simpson's phone number would also match because there is a space followed by two digits - " 55" - just not at the end of the filename.

To learn more about regular expressions, see or jump straight to the examples if you're pressed for time.

Audio Tags

If you are renaming audio files (such as MP3 and M4A) you can use the following tokens in the New box. If you only wish to rename files based on these tags (and discard existing filenames), then the Old box may be empty:

  • $a - artist
  • $b - album
  • $c - composer
  • $g - genre
  • $t - title

Cut and Paste

Cut and Paste should be fairly straight forward; it allows you to remove any number of characters from any location in a filename or to paste text at any location.

Cut and Paste - cut options

In this example, 20 characters have been removed after the 5th character in the file name. The other file in the picture below has not been affected because it is shorter than 20 characters.

Cut and Paste - cut preview

You can also Cut 3 at -3 to remove 3 characters from the end of each filename:

Cut and Paste - cut at negative index preview

Paste allows you to insert text at any location.

Add Numbers

Add Numbers allows you to add a custom sequence of numbers to your files:

Add Numbers - options

In this example, the sequence starts with the number 90 at the beginning of each filename, then steps (or increments) by 10 for each subsequent filename. It also pads the numbers using three zeros so that everything lines up once the number goes beyond 90:

Add Numbers - preview

This example also uses Paste to add a hyphen surrounded by spaces so that there is a gap between the numbers and the existing filenames.

You might be wondering why the Add Numbers and the Paste actions both use a position of zero. Because the Cut and Paste action is located above the Add Numbers action, its position zero is the old filename before anything has been added. So Paste adds " - " to each file, then Add Numbers receives these modified filename previews and uses position zero as its starting point, which adds the numbers before " - " and is ignorant of what Cut and Paste has done already.

You can use the up and down arrows at the top of each action to change the order to suit your requirements.


The miscellaneous set of actions provides a facility to change the case and to add the date and time to the filename itself. Case options are:

  • Sentence caps - Capitalise the first character
  • Word Caps - Capitalise Every Word
  • lower case - change all characters to lower case

The case of the file extension also can be changed regardless of which option you have selected for "Process" beneath the Preview button

The created (or modified, opened, or added) date can be added to the filename using a sequence of characters describing the desired format, such as:

  • mm.dd.yyyy h:mm a - (09.21.2015 8:31 am) hour:minutes AM/PM (two "h" characters would include a leading zero to the hour where necessary)
  • d MMM yyyy - (21 September 2015) day Month year (day without leading zero, full name of the month)

A full list of supported date format characters can be found in Unicode Technical Standard #35.

Miscellaneous - options

This example shows Word Caps with the Created date being added to the filename (you may also add other characters before or after a date format instead of using Paste, if you wish):

Miscellaneous - preview

At the bottom of the Miscellaneous set of actions is a very powerful way to adjust all numbers in file names quickly and easily. Say you need to subtract 5 from all numbers at or after a certain point in each file. Consider the following example:

Miscellaneous - adjust numbers

This example looks for any number at or after position 7 (indicated by the highlight which moves as you specify the "near" index) in each file, and if it finds one, subtracts 5. Although there are no numbers at position 7, Renominator still searches for the nearest number to the right (ignoring any to the left). You do not need to be exact when adjusting numbers; near enough is good enough here.

Miscellaneous - preview of adjusted numbers






Release History


  • Approved by Apple on 5 Jun 2016.
  • Added an extra option beside the Case combo box to treat file extensions separately
  • Fixed a bug which resulted in some file names ending witha dot unnecessarily (which prevented renaming)


  • Approved by Apple on 9 Jan 2016.
  • Added support for common audio file meta tags (ID3) in the Format Filename action’s New box ($a: artist, $b: album, $c: composer, $g: genre, $t: title)
  • Added a proper help file to the Help menu (instead of loading the Renominator web page in a browser)
  • Added the “Edit > Check Only Selected” and “Help > Email the Developer” menu items
  • Fixed bug that prevented the “new profile...” combobox item from saving the new profile (the Save button still worked if no profile was selected)
  • Fixed bug which caused the following error to be shown incorrectly when entering a regular expression: “No matches were found in the pattern”


  • Approved by Apple on 4 Dec 2015.