Guide
Are online converters actually safe?
In 2025, the FBI's Denver field office issued a public warning about free online file converters. Not a hypothetical: real sites, ranking in real search results, using the convert-my-file moment to deliver malware or quietly read the documents people upload. Here's what the scam looks like and how to protect yourself – including from us, since healthy skepticism shouldn't make exceptions.
What the FBI actually warned about
The warning describes free conversion sites that do convert your file – so nothing seems wrong – while also doing one or both of: bundling malware into the downloaded result, or scraping the uploaded document's contents. Ebooks and manuscripts are documents; uploaded files can carry names, addresses, financial details, or a book you haven't published yet.
Why the upload is the whole problem
Every conventional converter works by taking your file onto its servers. From that moment, what happens is invisible to you: whether it's deleted, retained, read, or resold is entirely a matter of trust in an anonymous website. Most upload converters are honest. Some aren't. You cannot tell which is which from the outside – the honest and the malicious sites look identical, and both really do return a converted file.
The checklist for any converter site
- Does it work offline? The one test that can't be faked. Load the page, switch off wifi, convert. If it succeeds, your file physically couldn't have been uploaded. If it fails, it went to a server.
- Is there an upload progress bar? A "%uploading" bar is the tell that your file is leaving. (A processing bar is different – watch your network indicator.)
- Is the engine open source? Code that can be inspected is code that can be caught lying.
- Scan the output. Whatever converter you use, let your antivirus look at the downloaded file – that's the FBI's own advice.
- Never upload what you can't afford to leak: manuscripts, contracts, anything with financial or personal data. Convert those locally or not at all.
Applying the checklist to ebook.tools
We built this site so it passes its own audit. Every conversion runs in your browser – the airplane-mode test works here, on any tool page, any time. There is no upload bar because there is no upload; the site is static files with no server that could receive your books. The conversion engine is open source, so "runs locally" is a checkable claim rather than a marketing line. And we'd still tell you to virus-scan downloads as a habit, because the point isn't "trust us instead" – it's that you shouldn't have to extend trust at all.
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The FBI's warning boils down to one sentence: the moment your file leaves your machine, you've lost control of it. The fix is architectural, not behavioural – use tools where the file never leaves. For ebooks, that's exactly what this site is.