Resize images in batches using nothing but a browser. This project was born out of the need to conform large quantities of photos to a given dimension on a corporate computer with no adequate software installed. Keep in mind that Minimal Image Resizer is quick solution to make the pain go away, not a showcase of how to do such a thing properly.
Open src/index.html in any moderately recent browser of your fancy, select your images with the file browser and then save the resulting output images. You can also use the deployed version.