About this tool
Rewrite file extensions in one pass when export formats change, asset pipelines shift, or teams need a consistent extension list before delivery.
File Extension Changer replaces or appends file extensions across an entire name list in one step. Whether you are updating extensions after a format conversion, standardizing mixed-case extensions, or preparing an import manifest for a system that requires a specific extension, this tool handles the transformation instantly.
- Replaces extensions across multiple file names at once from a simple text list.
- Lets you keep lines without extensions or force a new extension onto every entry.
- Useful for migration checklists, CMS imports, and image conversion planning.
How to use Extension Changer
Paste your file name list, specify the current extension to match and the new extension to apply, then review the updated list. The tool preserves the base name and only modifies the extension portion, so you can copy the corrected names straight into your migration spreadsheet or script.
When this tool is useful
- Normalize file lists after converting assets from one format to another.
- Prepare CMS import manifests where all files must end in one expected extension.
- Rewrite planned export names before handing a batch job to ops or design.
Practical tips
- Only change the extension after the underlying file has actually been converted to that format.
- Use one clean lowercase extension style across every asset list to avoid mixed-case confusion in shared folders.
- Review entries without an existing extension separately if your upstream export process is inconsistent.
Examples you can test
These examples show the kind of real input and reviewed output this tool is designed to support. Use them as a starting point before pasting your own production content, then compare the output with the destination system that will use the result. The goal is not only to produce a value, but to make the input assumptions, output format, and review step clear enough that the result can be trusted in a real workflow.
Preview extension changes
Example input
image.jpeg -> image.jpg
Expected output
Renamed filename with .jpg extension
Changing an extension only changes the name, not the actual file format.
Normalize text file extensions
Example input
notes.text readme.text
Expected output
notes.txt readme.txt
Useful for cleanup when files were named inconsistently.
Validation checklist
Run through these checks before copying the result into a CMS, codebase, spreadsheet, campaign, support ticket, or production document. Small formatting differences, unit assumptions, hidden whitespace, and platform-specific rules are common sources of mistakes in quick browser tools, so the final review should happen in the same context where the output will be used.
- Do not treat extension changes as file conversion.
- Preview all renamed filenames before applying changes elsewhere.
- Check for duplicate names after extension normalization.
Why people use this tool
Mismatched extensions break file associations, cause MIME-type errors on web servers, and confuse downstream tools that rely on extensions to determine processing pipelines. Bulk-correcting extensions in a controlled preview environment prevents these issues from surfacing in production.
Related search intents
file extension changer, change extension online, bulk extension rename, replace file extension.