Bulk Rename Files Online – No Upload Required

Rename multiple files at once directly in your browser. Find & replace text, add prefixes or suffixes, change letter casing, and insert sequence numbers — all without uploading a single file.

How It Works

FileTango's Bulk File Renamer processes everything inside your web browser using modern JavaScript APIs. When you select files, the browser reads their names locally without transmitting any data over the internet. You then configure one or more renaming rules — such as find-and-replace, prefix/suffix additions, case transformations, or sequential numbering. The tool generates a real-time preview table showing the original name alongside the proposed new name, and flags any conflicts or duplicates. Once you are satisfied with the preview, click Download to receive a ZIP archive containing all renamed files. The entire pipeline — reading, renaming, and packaging — runs on your device, so your files stay private and the process is instantaneous regardless of your internet speed.

Step-by-Step Tutorial

Select your files

Click the "Select Files" button and choose the files you want to rename from your computer. You can select multiple files at once using Ctrl+Click (Windows) or Cmd+Click (Mac).
Configure renaming rules

Set up one or more rules: enter text to find and replace, add a prefix or suffix, choose a case transformation (lowercase, UPPERCASE, or Title Case), or enable sequence numbering with custom start, step, and padding values.
Preview the results

Click "Preview Changes" to see a side-by-side comparison of original and new file names. Green rows indicate successful renames, red rows show conflicts, and yellow rows are skipped files. Adjust your rules if needed.
Download renamed files

Once the preview looks correct, click "Download ZIP" to receive a ZIP archive containing all successfully renamed files. You can also export the renaming plan as a CSV file for your records.

Common Use Cases

Organize vacation photos by adding destination names and dates to file names
Add sequential numbers to podcast episodes or lecture recordings
Standardize naming conventions across project assets before sharing with a team
Clean up messy file names downloaded from the web or email attachments
Prepare product images for e-commerce uploads with consistent naming patterns
Rename scanned documents with meaningful labels for easier retrieval

Tips & Best Practices

Always preview before downloading — the preview catches conflicts and unexpected results before you commit.

Use the CSV export feature to keep a log of all name changes for your records or to share with teammates.

When adding sequence numbers, choose a padding of 3 or more digits (e.g., 001, 002) so files sort correctly in file explorers.

Combine multiple rules for complex renames: for example, lowercase everything, then add a date prefix.

Test with a small batch of files first to verify your rules produce the expected output before processing hundreds of files.

If you need different rules for different file groups, process each group separately and merge the ZIPs afterward.

Frequently Asked Questions

Is it safe to rename files with FileTango?

Absolutely. FileTango never uploads your files to any server. All processing happens locally in your browser using the File API. Your original files on disk are never modified — you receive a separate ZIP with the renamed copies.

What is the maximum number of files I can rename at once?

There is no hard limit imposed by FileTango. The practical limit depends on your device's memory and browser capabilities. Most modern computers can comfortably handle several thousand files in a single batch.

Can I undo a rename after downloading the ZIP?

Since your original files are never modified, there is nothing to undo. The ZIP you download contains new copies with the updated names. Your originals remain exactly as they were on your computer.

Does the tool preserve folder structure when renaming files?

The current version works with a flat list of files. All renamed files are placed at the root of the ZIP archive. If you need to maintain folder hierarchy, rename files from each folder separately.

Can I use regular expressions in the find & replace field?

The current version uses plain-text matching for find & replace. This covers the vast majority of renaming scenarios. For advanced pattern matching, combine multiple rules such as case change plus prefix/suffix.

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

FileTango automatically detects naming conflicts in the preview step. Conflicting entries are highlighted in red so you can adjust your rules before downloading. No files are packaged until all conflicts are resolved.

Privacy & Security

All file processing happens entirely in your browser using the Web File API. Your files are never uploaded to any server, never stored in any database, and never transmitted over the internet. We physically cannot see or access your files.

When you click Download, a ZIP archive is assembled locally in your browser's memory and saved directly to your computer's default download folder. The entire pipeline — from file selection to ZIP creation — runs on your device.

FileTango does not require an account, does not collect personal information, and does not track which files you process. Your privacy is guaranteed by architecture, not just by policy.