Question 1

Is it safe to upload files to an online converter?

Accepted Answer

For a public file, it is a non-issue. For anything containing personal or commercial data — a contract, an ID scan, a medical letter, unreleased work, a customer export — uploading means transmitting that data to a third party and relying on their security, their retention policy and their jurisdiction. Reputable services encrypt transfer and delete files after a period, and that is genuinely a reasonable posture. It is still a weaker guarantee than a tool where the file never leaves your device, because then there is nothing to retain, breach or hand over.

Question 2

What is the catch with a free, in-browser converter?

Accepted Answer

Two real ones. First, format coverage: a browser has codecs for images, audio and a handful of document formats, so video, CAD and most office-document conversion is out of reach — a server can run any tool, and that is a genuine advantage. Second, file size: a browser tab typically has 250-500MB of memory, so gigabyte-class files can fail where a server would not. Within those limits, there is no catch — the compute happens on your machine, which is why there is nothing to charge for.

Question 3

How can I verify that my files aren't being uploaded?

Accepted Answer

Open your browser's developer tools, switch to the Network tab, then drop a file and convert it. You will see the page's HTML, its JavaScript, the WebAssembly codec bundles and an analytics ping — and no request carrying your file. You can also disconnect from the network entirely after the page loads; the tools keep working, which they could not do if a server were involved.

Question 4

Which converter should I actually use?

Accepted Answer

It depends on the file. For images, PDFs, spreadsheets, data files, fonts and audio — the everyday cases — an in-browser tool is faster and does not require trusting anyone. For video, CAD, office documents, OCR or anything over about half a gigabyte, a server-side service is the right tool and convert.now will not help you. The comparisons below say which is which for each service.

Alternatives to upload-based file converters

convert.now vs Convertio

convert.now vs CloudConvert

convert.now vs Smallpdf

convert.now vs TinyPNG

convert.now vs iLoveIMG

Choosing a file converter: common questions