Batch Rename Files

About Batch Rename Files Tool

This tool renames multiple files at once with three modes: Pattern (prefix, suffix, sequential numbering), Regex find/replace (capture groups to rearrange names), and Case Transform (lower, UPPER, Title, kebab-case, snake_case, trim spaces). Preview every new name, auto-resolve duplicate-name collisions, export an old-to-new CSV undo log, and download results individually or as a ZIP. Perfect for organizing photos, documents, or dataset prep. All processing happens in your browser for complete privacy. Try also our Merge Files and 7Z Extractor.

What is batch renaming and when do I need it?

Batch renaming is the process of changing the names of many files at once according to a rule, instead of right-clicking each one. Common scenarios include (1) organizing a folder of photos imported from a camera with cryptic names like DSC_0001.jpg into something descriptive like 2026-05-vacation-001.jpg, (2) sequentially numbering audio tracks ripped from CDs, (3) standardizing inconsistent naming across a team's shared folder, (4) replacing spaces or non-ASCII characters in filenames before uploading to a server, and (5) prefixing or suffixing all files with a project code. Doing this by hand on more than a dozen files invites typos and inconsistency; a batch tool applies the same rule deterministically and lets you preview the result before committing.

What renaming patterns and rules can I use?

Most batch renamers support a small set of composable rules: (1) Find and Replace — change every occurrence of a string, with optional case sensitivity and regex support, (2) Add Prefix/Suffix — prepend or append fixed text, often with a counter token like {n} that auto-increments, (3) Sequence numbering — number files 001, 002, 003 with a chosen start and padding width, (4) Change Case — uppercase, lowercase, Title Case, sentence case, (5) Insert Date/Time — embed today's date, file creation date, or EXIF capture date, (6) Remove Characters — strip from a position or by character class, (7) Extension change — convert .jpeg to .jpg or .JPG to .jpg. Rules can usually be chained — apply Find/Replace first, then add a date prefix, then renumber.

How do I safely test renames before applying them?

Always use the preview mode before committing. A good batch renamer shows a two-column table with the current name on the left and the proposed name on the right, highlighting any collisions (two files renaming to the same name) and any rule failures (e.g., trying to insert EXIF date on a file with no EXIF). Before clicking apply, scan the preview for unexpected changes — a regex that matches more than you intended, a case change that breaks a known reference, or a sequence that resets unexpectedly when sorting differs from expectations. For irreversible renames, also copy the folder to a backup or use a tool that writes an undo log. On Linux, the rename -n flag shows what would happen without doing it; on this tool, the preview pane serves the same purpose.

What is a regular expression and why is it useful for renaming?

A regular expression (regex) is a compact pattern language for matching text. In a batch renamer, regex unlocks operations that simple find-and-replace cannot do: capture parts of a name and rearrange them. For example, the pattern ^(\d{4})-(\d{2})-(\d{2})_(.+)$ with replacement $4_$1$2$3 turns 2026-05-17_meeting.txt into meeting_20260517.txt. Common building blocks: \d matches a digit, \w matches a word character, . matches any character, + and * mean one-or-more and zero-or-more, [] defines a character set, () captures a group, $1 $2 $3 reference captured groups in the replacement, ^ and $ anchor the start and end. Most batch renamers use ECMAScript or PCRE regex flavors. Test patterns on regex101.com before applying to real files.

What happens if two files would end up with the same name?

This is called a collision, and every batch renamer must handle it. Three common strategies: (1) Refuse — the tool detects the collision in preview and refuses to apply until you change the rule, which is safest, (2) Append suffix — automatically add (1), (2), or _01, _02 to disambiguate, which preserves all files but may surprise you, (3) Overwrite — keep only the last file written, which silently destroys data and should be off by default. Always check the preview for any duplicate target names highlighted in red before applying. Common collision causes: (a) renaming photos by date when many were taken in the same second, (b) stripping all numbers from filenames that differed only by number, (c) lowercasing on a case-sensitive filesystem where IMG.JPG and img.jpg currently coexist. Add a counter token to the rule to avoid collisions.

Can I rename files based on their EXIF or metadata?

Yes — many batch renamers can read EXIF, ID3 (MP3 tags), or filesystem timestamps and embed them in the new name. Typical tokens are {ExifDateTimeOriginal:YYYY-MM-DD}, {ID3:Artist}, {ID3:Title}, {Camera:Model}, {GPS:City} (via reverse-geocoding). This is especially powerful for photo libraries: a batch rename rule like {ExifDateTimeOriginal:YYYY-MM-DD}_{ExifDateTimeOriginal:HHmmss}_{ExifCameraModel}_{n:04} produces names like 2026-05-17_142336_NIKONZ8_0042.jpg that sort chronologically and tell you the device and sequence at a glance. For music, {ID3:Albumartist}/{ID3:Album}/{ID3:Track:02}_{ID3:Title}.mp3 reorganizes a chaotic dump into a clean Artist/Album/Track structure. Always verify the metadata exists on all files before applying — missing fields can produce empty tokens that collapse multiple files together.

Are file renames reversible, and what should I do if something goes wrong?

A rename on most filesystems is a metadata operation, not a data copy, so it is fast but also instantly destructive — there is no recycle bin for the old name. This tool protects you in two ways: it never overwrites colliding files (with Auto-resolve enabled it appends _01, _02 so every file survives), and the Download Rename Map (CSV) button exports a two-column old-to-new log you can keep as an undo record. If you discover an error after applying, recovery depends on whether you kept that log. If you do not have one, the only recovery is to restore from backup (Time Machine, Windows File History, cloud sync history). To stay safe, (1) always check the preview before applying, (2) work on a copy of the folder for large operations, (3) download the CSV rename map, and (4) avoid changing extensions in bulk without verifying the new extension is correct for the file's actual content.

Is this tool private, and how many files can it handle at once?

Everything runs 100% in your browser — your files are never uploaded to any server, so the tool also works offline once the page has loaded, which is ideal for confidential document sets or proprietary datasets. Practical limits come from your device's memory, not a server quota. Renaming and individual downloads scale to thousands of files, but the ZIP download holds every file's bytes in RAM while building the archive, so very large batches (for example several gigabytes of photos or video) can exhaust memory and fail on low-RAM devices. For huge sets, prefer Download All or split the batch, and use the CSV rename map plus your OS rename tool to apply names without re-downloading the file bytes.

What characters and length limits should I avoid in filenames?

Filename rules vary by filesystem and operating system. Windows (NTFS, FAT32, exFAT) forbids the characters \ / : * ? " < > | and reserves device names CON, PRN, AUX, NUL, COM1–COM9, LPT1–LPT9. macOS and Linux (APFS, ext4, btrfs) are far more permissive but still treat / as a path separator and choke on filenames with NUL bytes. Maximum filename length is typically 255 bytes on most modern filesystems, which is 255 ASCII characters but only about 63 characters in UTF-8 if every character is 4 bytes (rare emoji). Full path length on Windows is capped at 260 by default unless long paths are enabled. For maximum portability across Mac, Windows, Linux, web URLs, and email attachments, restrict filenames to ASCII letters, digits, hyphen, underscore, and period; avoid leading hyphens (mistaken for command flags) and trailing spaces or dots (Windows silently strips them).