PhotoShow is a free, open-source, PHP application and very easy to use web image gallery installable on any web server.
The application works without a database and uses the folder structure for creating the hierarchy of the galleries (supports unlimited sub-galleries).
Images can be added either from the admin panel via a drag ‘n’ drop uploader or directly from the filesystem. Organizing the folders/images, editing and deleting them are also accomplished with the same methods.
There is support for multiple users and groups where each can have different permissions.
PhotoShow can auto-generate thumbnails of images, display the EXIF data and allows others to comment them.