TinyJPG compresses on its servers: its own page says every uploaded image is analyzed when you upload a JPEG file. A browser-based image compressor re-encodes JPEG, PNG and WebP images on your own device, so the photo is never uploaded at all.
TinyJPG is a well-known compressor, and its own description explains that when you upload a JPEG file the image is analyzed on its side to pick an optimal encoding. That is effective, but it means the picture travels to its servers. A client-side compressor decodes and re-encodes the image directly in your browser, choosing a quality level you control, so the same size savings happen without the file ever leaving your machine.
Local compression is the safer default when the image is a private photo, an unpublished product shot, or a screenshot with personal details, because nothing is uploaded and nothing is stored. You can compress a single image or work through several one after another, checking the before and after size each time, with no account to create.
No. Compression runs entirely in your browser, so the photo never leaves your device.
Common web formats including JPEG, PNG and WebP, all compressed locally.
No account limit; you are bounded only by your device memory.