There is no upload step
Most converter sites take your file, put it on a server, convert it there and hand it back. OnlineFile does the conversion in the page you are reading. That single decision explains every other choice here.
Why local conversion
A lot of the files people need to convert are passports, signed contracts, medical scans and internal screenshots. Uploading those to a stranger’s server to change a file extension is a poor trade. Browsers can now decode images, parse PDFs, run OCR and re-encode audio on their own, so the upload is no longer necessary.
What that costs you
Conversion speed depends on your device rather than our hardware, so a large video re-encode is slow on a phone. Some formats need licensed codecs we cannot ship, and colour-managed or 16-bit work belongs in a desktop tool. We say so on the tools concerned instead of failing halfway.
How it is paid for
Ads on some pages cover hosting. There is no paid tier, no sign-in, and no analytics on file contents — we cannot measure what never reaches us.