Batch File Extension Renamer

Replace file extensions with collision checks and download copies with unchanged contents.

Choose your files

Private by designProcessed locally · Originals unchanged

Choose local input and settings.

Preview & downloads

Your result will appear here

Choose a file, adjust the settings and select Rename Files.

How to use, limits & privacy

Select 1–100 files, enter an extension and review the old-to-new names before clicking individual download links. Last extensions are replaced; dotfiles and extensionless names get the new extension appended, subject to portable filename rules. Names are checked for case-insensitive normalized collisions. This changes names only and does not convert file formats. Maximum 32 MiB per file and 128 MiB selected total. Downloaded copies use application/octet-stream; original files remain untouched.

File inventory reads properties only. Byte Inspector reads bounded slices. Extension Renamer creates separate downloads.

Inputs are never uploaded. Results are rendered as text or a locally generated image. Original files remain unchanged. Changing input invalidates previous results.