: In the "Replace with" field, type the extension you want to add, starting with a period (e.g., .jpg or .txt ).
: Check the preview pane to ensure the new filenames look correct, then click Apply . Essential Tips for Success
(optional but recommended) In PowerRename search box, enter: ^[^.]+$ Check Use Regular Expressions . Only extension-less files appear.
File extensions (e.g., .docx , .png ) allow operating systems to map files to default applications. When a file lacks an extension, Windows treats it as a "File" with no type, preventing double-click opening and breaking automated workflows. PowerRename provides a safe, GUI-based solution to add extensions in bulk without scripting.
To add an extension to files that currently have none using , you can use a regular expression to target the end of each filename and append the desired extension. Quick Steps to Add Extensions
– also exclude files starting with a dot (Unix hidden files): Better pattern: ^(?!\.)[^.]+$ But PowerRename's regex engine (C++ std::regex) may not support lookaheads. Simpler: use ^[^.]+$ and manually skip dotfiles.