Offline ConverterHow to convert a file without uploading it anywhere
Most “free online converter” sites work by taking your file onto their server, converting it there, and giving you a link. For a meme, fine. For a signed contract, an NDA'd cut of a film, a passport scan or a client's medical form, that's a data transfer to a third party you've never heard of — and often one your employer's policy forbids.
What the terms actually say
Reputable converters (CloudConvert and Zamzar among them) do publish real retention policies — typically deleting files automatically after a fixed window, with encryption in transit. They are not villains, and for most files they're fine.
The problems are the other ones: the ad-funded sites that rank for the same queries, whose privacy policy is a template, whose retention period is unstated, and whose business model depends on traffic rather than trust. You cannot tell them apart from the search results page, and once the file is uploaded the decision is no longer yours.
There's a simpler test than reading policies: if the file never leaves the machine, there is nothing to trust and nothing to delete.
What macOS already does locally
More than most people realise, and it's all free.
- Images: Preview converts and resizes single files or whole selections (File → Export / Export Selected Images).
- Video: QuickTime exports to 4K/1080p/720p H.264.
- PDF: Preview merges, splits, rotates and compresses; any app's Print dialog can Save as PDF.
- Everything else: ffmpeg via Homebrew converts essentially any audio or video format ever made, if you're comfortable in a terminal.
Where the gaps are
The built-ins have no batch worth the name, no RAW photo support, no HEIC-to-anything beyond Preview's export, no document conversion, no target-size compression, and no memory of what you did last time. ffmpeg has all the power and a syntax you re-google every single time.
That's the whole reason this app exists: the coverage of the cloud converters, on your own machine, in one window. Free for three days, $29.99 once after that — and the only network request it ever makes is checking your license key.
Common questions
Is CloudConvert safe?
For ordinary files, generally yes — it's an established company with a published retention policy and paid plans, which means its business model isn't your data. Whether it's appropriate for confidential material is a different question, and one your organisation may have already answered for you.
How can I tell if a converter uploads my file?
If it runs in a browser tab and you didn't install anything, assume it uploads unless the page explicitly says it converts in-browser with WebAssembly. A native app can be checked directly: turn off Wi-Fi and try to convert something. If it works, nothing is being uploaded.
Does this app work offline?
Yes, entirely. Conversion engines are bundled and run locally — you can convert with the Wi-Fi off, on a plane, for as long as you like.
Keep reading
This guide is currently available in English only.