Curtail vs Kraken.io

Curtail is a free Linux application for compressing PNG, JPEG, WebP, and SVG images. It offers both compression modes and lets users decide whether image metadata is retained. Recursive directory compression supports batch processing across folder contents. When compression would produce a larger file, Curtail restores the original. Actions are provided to open a compressed image and reveal it in its folder. The project is released under the GNU General Public License version 3 or later and uses open-source components including Oxipng, pngquant, Jpegoptim, libwebp, and Scour. The project recommends installing its Flatpak package from Flathub; unofficial Snap, Ubuntu PPA, and Fedora COPR packages are also listed. Flathub marks the app as potentially unsafe and lists read/write access to the home folder. The GNOME page lists version 1.17.0, released on 2026-10-05, and links to an issue tracker. Curtail is available at no cost, with no trial required.

Kraken.io is an image optimization service with a browser tool and an API. In the browser, it can optimize, compress, resize, and convert images without code; it also accepts ZIP archives and returns a processed archive. Supported formats are JPG, PNG, WebP, GIF, SVG, AVIF, HEIC, and PDF. The service offers batch processing, metadata controls, and both listed compression modes, with a maximum upload size of 32. Each account starts with 100 MB of testing quota, and signup does not require a credit card. Monthly quota is measured by unprocessed source image data before overage charges. Plans include Free, Micro, Basic, Advanced, Premium, and Enterprise; the pricing note lists paid service from $5/mo. Customers can choose monthly or yearly billing and cancel, downgrade, or upgrade without a contract. Official plugins are available for WordPress and Magento.