Yes, by design, on every device. No sign-up, no software, no app to install, HTTPS only, one real download button and no fake ones.
Converter apps from outside the app stores are a classic malware vector. A website that installs nothing cannot install malware. On iPhone and Android alike, the browser is the safest place to convert because it is sandboxed by the OS.
For the testing methodology, see our sister site's converter safety test.
Yes, by design. No sign-up, no software, HTTPS only, one real download button.
Yes. It runs in your mobile browser and installs nothing, so there is no app to carry malware.