Batch File Renamer

Rename multiple files using patterns: find/replace, numbering, date prefix, regex, and case change.

Tested tool guide Tested browser tools Checked August 16, 2026

What Batch File Renamer does, with a checked example

Batch File Renamer creates a new name for every selected file by applying a repeatable naming rule. It supports literal find/replace, sequence numbering, a date prefix, regular-expression matching, and letter-case changes. File contents are not converted or edited, and the work stays in the browser rather than being uploaded. The easy mistake is to judge one successful rename and assume the entire batch is safe. A broad pattern can collapse different originals to the same target name, so review every original-to-result pairing.

Worked example

A concrete input and expected output from the current implementation.

Input

Selected files:
draft-notes.txt
draft-budget.csv

Find: draft
Replace with: final

Expected output

final-notes.txt
final-budget.csv

Each original name contains one occurrence of draft. Replacing that text with final leaves the remaining name and file extension unchanged.

How the result is produced

From source to target

For each selected file, the tool starts with the original filename and calculates a target filename from the configured rule. Literal replacement substitutes specified text, numbering adds a sequence, a date prefix places date text at the front, regex handles pattern-based matches, and case mode changes capitalization. These operations affect filenames only, so the underlying file content remains the same.

Interpreting the batch

Treat the result as paired source and target names rather than as an unrelated list. Files that do not satisfy a find or regex condition may remain unchanged, while rules that remove distinguishing text can produce identical targets. Numbering is order-sensitive, so inspect batch order as well as the pattern. Resulting names must also satisfy the filename restrictions of the system where they are saved.

Good uses

Replace an obsolete project code across a folder of exported reports without opening or editing the reports themselves.
Add sequence numbers to scanned page images so their filenames preserve the intended reading order when sorted.
Normalize inconsistent capitalization in collected assets, or add a common date prefix to one group of downloaded invoices.

Limits and checks

A rename rule does not guarantee unique output. Distinct originals can become the same target name after text removal, replacement, or case conversion.
Regex mode interprets pattern syntax rather than every character literally. An overly broad expression can match and alter more filename text than intended.
Sequential numbering depends on batch order. Do not assume that order matches a file manager's alphabetical, numeric, modification-date, or creation-date view.

Common questions

Does renaming a file convert it to another format?

No. The tool changes filename text, not the encoded data inside the file. A renamed photo remains the same photo format, and a renamed archive remains the same archive format. Use a format converter when the contents must change. A filename suffix that no longer agrees with the actual data does not perform or prove a conversion.

When should I use regex instead of ordinary find and replace?

Use find/replace when every relevant filename contains the same exact text. Use regex when the portion to match has a repeated structure but varying characters, such as runs of digits with different values. Regex is not automatically better: metacharacters can widen a match unexpectedly. Test the rule against the complete batch and do not assume unmatched names were changed.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.