Have you ever tried to upload a photo or other image only to have them rejected because of size? I certainly have. It's annoying.
There's a remedy for that at Online Image Compressor.
It's super simple to use. Just drop your image or images into the area marked "Drop Your Files Here" or click on the button "Upload Files" and let the image compressor do the magic. When it is done, you will see a comparison of the original and compressed images. You will have a choice of redoing the compression or uploading a zip file of the image or images that you've compressed.
When you are happy, upload the images and unzip them. They should be small enough to share them on the website of your choice.
I was able to reduce two images of over 8mb to around 430K. There was color loss and some edges were jagged, but it was more than acceptable for the reduced size!
The ZIP file went through a VirusTotal scan before being opened and came back clean. It contained two images, which was exactly what I expected.
The website has a couple of sane, still advertisements and no pop-ups on Firefox with no adblocking. The instructions and site tools are clearly separate from the ads.