NoiseNinja 2.2.0 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The application lies within Design & Photo Tools, more precisely Viewers & Editors. We recommend checking the downloaded files with any free antivirus. The following versions: 2.3 and 2.2 are the most frequently downloaded ones by the program users. The actual developer of this free software for Mac is PictureCode LLC.
From the developer:
Noise Ninja is the most effective and productive solution for removing noise and grain from digital photographs and scanned film images. It is a must-have tool for anyone shooting in low-light or fast-action situations -- including news, sports, wedding, and event coverage -- where high ISO photography is required and the resulting noise compromises the image.
You may want to check out more Mac applications, such as Noise Ninja for Photoshop, which might be similar to NoiseNinja.