Three kinds of converter
| Type | Where the work happens | Typical limits | Privacy model |
|---|---|---|---|
| Server-based web tool | Their servers | File size and daily quotas; paid tiers | Your images are uploaded and stored for a period under their policy |
| In-browser web tool | Your browser tab | Memory of the tab; HEIC rarely supported | Files stay local, but you must trust that the page does what it says |
| Native app (ConvertX) | Your device | Your storage | No network path for files exists; the desktop app uses no network at all |
Where online tools are better
- One-off conversions on a machine where you can't install anything.
- Formats ConvertX doesn't handle: PDF, SVG, RAW, PSD, ICO, video.
- Reading AVIF (ConvertX only writes it).
Where an offline app is better
- Batches: hundreds of files through one queue, with no quota.
- Personal photos: nothing is uploaded, and location data is stripped by default.
- HEIC on Android: the system decoder does the job; browsers mostly can't.
- No connection: planes, field work, metered data.
What ConvertX doesn't do
It is an image tool only: no video, audio, PDF, SVG, RAW or cloud storage, no iOS version, and no browser version. AVIF can be written but not read; HEIC is read on Android 9+ only. See the FAQ.
Frequently asked questions
Are online converters unsafe?
Not inherently. Reputable ones delete uploads after a while and publish a policy. The point is that you are trusting that policy with each photo; an offline app removes the question.
Don't some online tools convert in the browser without uploading?
Some do, using JavaScript or WebAssembly, and that is genuinely private for the formats they support. They still need the page to load, usually cap the batch size, and can't open HEIC on most browsers.
Why not just use the online tool for one file?
For one non-sensitive file, do. ConvertX is for batches, for photos you'd rather not upload, and for working with no connection.