Free, ad-supported, and entirely browser-based — nothing you open ever leaves your device. Every tool below runs as WebAssembly and Canvas code inside your own tab, so there is no upload step, no account and no queue to wait in.
Two jobs get confused constantly. Resizing changes an image’s pixel dimensions — use it when a form asks for something like 600 × 600. Compressing changes the file size in kilobytes while leaving the dimensions alone — use it when the upload limit is stated in KB or MB. A photo can easily be the correct dimensions and still be rejected for being too large a file, and the fix for that is compression, not resizing.
Format matters just as much. JPG suits photographs, PNG suits screenshots, logos and anything needing transparency, and WebP usually beats both on size when you control where it is going. If a site refuses your iPhone photo outright, the cause is almost always HEIC — convert it to JPG and the same image will go through.
Conventional online tools work by sending your file to a server, processing it there and sending it back — which means a copy of your document exists on somebody else’s machine, however briefly. SpecShot does the processing in the browser instead, so that copy is never created. It also means the tools keep working with no connection once the page has loaded, and that there is no account to create or queue to wait in. What that does and does not cover is set out in the Privacy Policy.