How is this different?
Most "online" converters upload your file to their server, process it there and send it back. That's slower, and it means a copy of your photo or document sits on someone else's computer. These tools use your browser's built-in capabilities instead. Every page has a security policy that stops it from sending data to any server. After a page loads you can go offline and it keeps working.
Free, with no sign-up
There's no account, no watermark and no daily limit.