Free Bulk File Renamer

Worked example

Add IMG 0412.JPG, IMG 0413.JPG and IMG 0414.JPG, then set "Letter case" to "lower case", "Spaces" to "Use _" and "Extension" to ".jpg (lower)". The "New name" column shows img_0412.jpg, img_0413.jpg and img_0414.jpg, and the line at the top of the page reads "3 files · 3 renamed". With those settings still on, tick "Add a number", set "Where" to "Instead of the name", keep "Digits" at 001 and type "Italy " in "Prefix". The names become Italy 001.jpg, Italy 002.jpg and Italy 003.jpg, because the prefix is added after the case and spaces rules have run. "Download 3 renamed files (ZIP)" saves renamed-files.zip, and your original files are not changed.

Which settings to use, and the limits

• Read the "New name" column before you download. The table puts every new name next to the current one, and names that change are shown in teal. The rules run in a fixed order on the name without its extension: "Find", then "Letter case", "Spaces", "Remove accents (é → e)", "Add a number", "Prefix" and "Suffix", "Add a date", then a safe-character clean-up and the "Extension" setting. Because letter case runs before the prefix, suffix, number and date, a prefix such as IMG_ keeps its capitals even when "Letter case" is "lower case". The table lists the first 300 files and then says "…and 12 more" with your own count; the rest are renamed by the same rules.
• Use "Find" for patterns, not for the extension. "Find" and "Replace with" work on the name without the extension, so use the "Extension" setting to change .JPG to .jpg. Matching ignores capitals unless you tick "Match capitals". Tick "Regular expression" for patterns: with "Find" set to (\d{4})-(\d{2})-(\d{2}) and "Replace with" set to $3.$2.$1, 2026-03-07 Report.pdf becomes 07.03.2026 Report.pdf. With that box unticked, both fields are plain text, and a dollar sign in "Replace with" stays a dollar sign.
• Choose the order before you number. "Add a number" gives each file a number by its place in the list, starting at "Start at" and growing by "Step". "Order" sets that place: "As added" keeps the order the files were added in, "By name" sorts names so that img2 comes before img10, and "By file date" sorts by each file's last modified date. "Digits" offers 1, 01, 001, 0001 and 00001, and the default is 001. "Separator" takes up to 5 characters, and "Where" puts the number before the name, after it, or instead of it. A "Step" typed as 0 is treated as 1.
• Put the date in the name. Tick "Add a date" and choose "Which date". "Date the photo was taken (file date if none)" reads the camera date from JPEG, HEIC, HEIF, TIFF, PNG, WebP, AVIF, DNG, CR2, NEF and ARW files, and uses the file's last modified date for every other file. "File date (last modified)" always uses the last modified date. The formats are 2026-03-07, 20260307, 2026-03-07_14-05-09 and 07-03-2026 (day, month, year), and "Where" puts the date before or after the name. It is joined with an underscore, which you cannot change, and it sits outside any prefix or suffix. For example, IMG_0412.JPG taken at 14:05:09 on 7 March 2026 becomes 2026-03-07_14-05-09_IMG_0412.JPG.
• Names are cleaned up for common file systems. Whatever the rules produce, the characters / \ : * ? " < > | and control characters become _, dots and spaces at the end of a name are removed, and a name such as CON, PRN, AUX, NUL, COM1 to COM9 or LPT1 to LPT9 gets an underscore added. A name is cut to 200 characters before the extension, and a name that ends up empty becomes _. "Remove accents (é → e)" strips accent marks from Latin, Greek and Cyrillic letters and leaves other scripts, such as Japanese, alone. When two files would get the same name, ignoring capitals, the later ones get " (2)", " (3)" and so on.
• Choose how to get the files back. "Your original files are not changed: you get renamed copies." "Download N renamed files (ZIP)" saves renamed-files.zip. The files go into it without compression, and a ZIP made here cannot hold 4 GB or more in total or more than 65,535 files. In browsers that let a page write into a folder, a "Save into a folder" button also appears. It never overwrites a file already in that folder (it adds (2) instead), and if you close the folder picker nothing is saved and no message appears. "Download the list of old and new names (CSV)" saves rename-list.csv with the columns old_name and new_name, so you can check the change or reverse it later.

Common problems and how to fix them

Under the "Find" box it says "This regular expression is not valid." and both download buttons are greyed out.

The pattern cannot be compiled. Common causes are an unmatched bracket or parenthesis, a pattern that starts with *, and a backslash before a character that does not need one: \-, \_ and a backslash before a space are all rejected, so type -, _ or a plain space without it. Escape only characters that have a special meaning, such as \. for a dot and \( for a bracket. If you only want to replace plain text, untick "Regular expression" and the text is matched exactly as typed.

Some new names end in (2) or (3) that you did not ask for.

Two or more files came out with the same name, so the later ones get a number. Capitals are ignored, so Report.PDF and report.pdf count as the same name. For example, removing " copy" from report.pdf, report copy.pdf and Report Copy.PDF gives report.pdf, report (2).pdf and Report (3).PDF. Make the names differ on purpose: tick "Add a number", or add a date with the 2026-03-07_14-05-09 format. The file that comes first in the list keeps the plain name.

The date in the name is not the date the photo was taken.

The "Which date" setting decides. "Date the photo was taken (file date if none)" falls back to the file's last modified date for a photo that has no camera date inside it, and for every file that is not one of these types: JPEG, HEIC, HEIF, TIFF, PNG, WebP, AVIF, DNG, CR2, NEF or ARW. Other raw formats, videos and photos saved without their metadata therefore get the file date. Choose "File date (last modified)" if you want that date on purpose, or leave the date out. The page shows "Reading the dates the photos were taken…" while it looks the dates up.

It says "That is more than a ZIP can hold (4 GB). Save into a folder, or rename fewer files at a time."

The ZIP is written without ZIP64, so the files together must stay under about 4 GB, a single file must be under 4 GB, and the ZIP can hold at most 65,535 files. Rename in batches: download one group, press "Clear all", add the next group and download again. Your rules stay when you clear the list, so change "Start at" to carry the numbering on. If "Save into a folder" is shown in your browser, use it instead, because the files then go straight into a folder you choose and no ZIP is made.

It says "The renamed files could not be saved. Try fewer files at a time."

Something failed while the ZIP was being built or the files were being written into the folder. A file may have been moved or deleted, may be open in another program, or may be only a cloud placeholder (OneDrive, iCloud, Google Drive) that the browser cannot read; the page cannot tell which. Download cloud files to this device first, close other programs that use the files, and try again with a smaller group. A file that cannot be read at all is usually refused when you add it, with a message ending "save it to this device first, then choose it again."

How it compares

Windows, macOS and most file managers can rename several selected files to one base name with a counter, and a desktop bulk-renaming program is usually the better choice when you need to rename files in place across many folders at once or change tags and other metadata. This page works on the files you add and gives you renamed copies, as a ZIP or in a folder, so the originals stay as they are and you delete them yourself. It does not rename folders and does not change anything inside the files. The only metadata it reads is the date a photo was taken. What it adds is a preview of every new name before anything is saved, regular expressions, numbering in natural order and date stamps in one place, all running in your browser.