I have a rule: if a website asks me to upload something, I assume they keep a copy. Not because I'm paranoid, but because most of their privacy policies say exactly that.
This is fine for some things. Uploading a photo to Google Photos or sending one through WhatsApp —you're using a service, you know what you're signing up for. But when you just want to resize an image or change its format, do you really need to hand it over to a third party?
Think of it this way: there are two kinds of image tools.
Server-side tools —You upload ←their server processes it ←you download. Your image exists on their machine for at least a few seconds, possibly longer.
Browser-side tools —You open the page, your browser does the work, nothing goes anywhere. Your image stays on your device the entire time.
For most basic tasks like compression, resizing, and format conversion, the server doesn't need to be involved. The browser can handle all of it. So the only reason a tool requires upload is because they chose to build it that way.
A few real scenarios:
Product photos for a client. You're a freelance photographer or a small business owner. You need to compress 20 product shots. Do you want those images sitting on a random server?
Screenshots with sensitive info. Maybe there's an email address, an order number, or a private message visible. You crop it out, but did the server save the original?
Just the principle of it. It's your data. You shouldn't have to give it away just to resize a photo.
So I built some tools. They run in your browser. No upload, no server, no copies. It's not a new idea —Google had Squoosh years ago. But the more options like this exist, the easier it is to choose the private one.
Next time you edit a photo online, ask yourself: does this tool actually need my file? If not, maybe don't give it to them.