Are online file converters safe?
FilePresto publishes this page and makes its own file tools, which work without uploading your file. The facts below come only from each company's own published pages, linked in each guide, as they read on 28th September 2026. We have tried to be fair. If anything is out of date or wrong, email [email protected] and we will correct it.
Most well-known online converters publish some information about how they handle uploaded files. In most cases, the file is sent to the company's servers for processing, kept there for a period stated by the company, and then deleted. Whether that is acceptable depends on the file and on your own or your organisation's privacy requirements.
What happens when you upload a file
A typical converter website sends your file over the internet to the company's servers. The conversion happens there, the result is sent back to you, and both copies are deleted after a set time. During that time, a copy of your file exists on systems you do not control, in the location or locations described by the company.
Some tools work differently: they process files in your own browser, in software installed on your computer, or on servers your organisation runs itself. FilePresto works in your browser; the others are listed further down this page.
Five things to check before you upload
- How long the file is kept. Look for a stated period, such as one hour or 24 hours, and whether you can delete it sooner.
- Where it is processed. The country matters if you are handling other people's personal information.
- Who can access it. Look for a clear statement about whether staff or service providers may access files, and in what circumstances.
- Whether it is used for anything else, such as training artificial intelligence.
- Whether the company holds a security certification, such as ISO 27001. This shows the company manages information security to a recognised standard. It does not mean your file is not uploaded.
What seven popular converters say about themselves
| Service | Uploads your file | Kept for | Processed in | Certification named |
|---|---|---|---|---|
| CloudConvert | Yes | up to 24 hours | Germany (United States for users there) | ISO 27001 |
| iLovePDF | Yes | up to two hours (up to five years for signed documents) | European Economic Area | ISO/IEC 27001 |
| FreeConvert | Yes | up to 8 hours | Ireland (Amazon Web Services) | None named |
| Smallpdf | Yes | one hour in some cases, and a reasonable period in others, depending on the page and whether you have an account | European Union | ISO 27001 |
| Convertio | Yes | up to 24 hours for the converted file | Germany | Its providers hold ISO 27001 |
| PDF24 | Yes | usually one hour, for the online tools | European Union | None named |
| Zamzar | Yes | 24 hours to 7 days, depending on which of its pages you read | United States | None named |
When a tool that does not upload is the better choice
For everyday files, many people are comfortable with a reputable converter that deletes files quickly. The case for a tool that does not upload is strongest when the file is confidential or about someone else: signed contracts, client papers, payslips, medical letters, passport and driving licence scans, pupils' records, or anything a school, council or business holds about the public. Many organisations need to know which outside companies receive personal information and where; a tool that never sends the file keeps that question simple.
How to check whether a converter uploads your file
- Switch off your internet. Load the converter, then disconnect and try it. If it still works, the file is being handled on your device. If it fails, it needed to send the file somewhere.
- Watch the network log. On a computer, open your browser's developer tools, choose the Network tab and convert a file. A large outgoing request the size of your file means it was uploaded.
You can try both tests on FilePresto; how it stays private explains what you should see.
If you would rather not upload the file at all
- FilePresto (ours) runs in your web browser and never uploads the file; the page locks itself so it cannot send anything. See all the tools. Free for up to 5 files at a time.
- PDF24 Creator is a free program you install on your computer; PDF24 says it works offline, so files stay on your computer (PDF24 help page).
- Stirling PDF is an open-core PDF platform that an organisation can run on its own servers, or use as a desktop app (project page). It suits IT teams that want PDF tools inside their own network.
About this page
How we wrote it: every fact in the tables comes from the company's own website, and each is linked so you can read it yourself. We do not use forum posts, reviews or reports from elsewhere. Where a company's own pages describe the same thing differently, we show both. Pages checked on 28th September 2026; we aim to check them again every three months. Companies change their policies, so if a decision matters, read the linked page itself. Corrections: [email protected].