Online Batch File Extension Changer & Renamer

Batch rename file extensions and names in seconds. Convert `.jpeg` to `.jpg`, `.yml` to `.yaml`, or append custom numbering prefixes, then download all files in a single ZIP.

Multi-File Batch Processing Instant ZIP Download 100% Free & Client-Side

Select or Drag & Drop Multiple Files to Rename

Upload images, code scripts, documents, or data sheets. Files are renamed instantly in local browser RAM.

What is Batch File Extension Changing & Why Rename Extensions?

Operating systems rely on file extensions (the letters following the dot, such as `.jpg`, `.html`, or `.csv`) to identify which application opens a file. When downloading assets from content management systems, cameras, or databases, files often receive inconsistent or outdated extensions—such as `.jpeg` instead of `.jpg`, `.yml` instead of `.yaml`, or `.tsv` instead of `.csv`. Manually clicking and renaming dozens of files in Windows Explorer or macOS Finder is tedious. NexTools Batch File Extension Changer renames file extensions and prefixes in bulk and packages them into a clean ZIP download.

Key Capabilities

Batch Extension Substitution: Change extensions across dozens of files simultaneously with one click.
Custom Prefixes & Suffixes: Prepend project codes (e.g. `v2_`) or append version markers (e.g. `_clean`) to filenames.
Instant ZIP Packaging: Bundles all renamed files into a single `.zip` archive without multiple download popups.
100% Client-Side Privacy: Internal database exports, private photos, and proprietary documents are processed locally with $0 server cost.

Step-by-Step How It Works

Select Files: Click "Select Multiple Files" or drag and drop a batch of files into the browser.
Enter New Extension: Type the desired extension (e.g. `.png` or `.csv`) or click a quick preset.
Inspect Live Table: Review the side-by-side preview showing original versus new filenames.
Download Files: Click "Download All Renamed Files (.zip)" to save your organized bundle.

Frequently Asked Questions (FAQ)

Does changing a file extension convert the underlying binary data?

Changing an extension renames the file identifier. For compatible formats (like `.jpeg` to `.jpg`, `.tsv` to `.csv`, or `.txt` to `.log`), the file functions immediately. Complex codec conversions (like `.png` to `.webp`) require transcoding tools.

Is there a limit on how many files I can rename?

No. You can select dozens of files in a single batch without server queue limits or account restrictions.

Does NexTools store my files on a server?

Never. Renaming and ZIP packaging execute 100% inside your local browser via JavaScript Blob and File APIs.