I am looking for a software (preferably open-source) for MacOs, which is able to reduce the size of images in bulk.

I usually copy pictures to 'bear notes' or 'typora' which occupy large space as original copy whereas too small if set thumbnails.

  • What format are your images? tIff, jpeg, png?
    – Natsfan
    Jan 13, 2018 at 18:17

2 Answers 2


XnConvert is not open source, but it does the job. Drag and drop the images you want to edit, add an action (e.g. resize), change the output settings (e.g. filename, location, and format) and hit convert.


I use imageoptim from imageoptim.com to reduce the file size of my games images without too much recognizible quality loss. It can also strip metadata, file permissions, attributes, you can select quality of png, jpeg or gif files, and optimization level.

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