Are Online File Converters Safe? What the FBI Warning Actually Means
The FBI publicly warned about online file converters spreading malware. Here is what the warning means, what the real risks are, and the safer way to convert files.
In 2025 the FBI issued a public warning that scammers were using online file converters to push malware onto people’s devices, with consequences running to identity theft and ransomware. That is not a fringe security blog being paranoid. That is federal law enforcement telling the public that a tool millions of people use casually has become an attack vector.
Here is what the warning actually means, what the real risks are, and what to do instead.
The two separate risks
When you upload a file to a converter website, you are exposed to two different problems at once. They are worth separating because they call for different responses.
Your file goes to a stranger’s server. The moment you upload, your document leaves your machine and lands on infrastructure you do not control. Whatever was in that file, a contract, an invoice, a medical form, a photo with location data, now exists on someone else’s computer, subject to their retention policy, their security, and their honesty about both. Security researchers put it bluntly: if a file leaves your computer, you should assume it is not as safe as it could be.
The download can carry malware. This is the half the FBI flagged. Some converter sites slip malicious code into the file you download back, or trick you into installing software alongside it. You went in to convert a PDF and came out with a keylogger. The converted file looks normal. The payload is invisible.
The first risk is about your data being exposed. The second is about your device being compromised. A sketchy converter can hit you with both in a single transaction.
Why “just pick a reputable one” is incomplete advice
The standard guidance is to read the privacy policy and stick to well-known tools. That is not wrong, but it is incomplete, because it still leaves your file sitting on someone else’s server. Even a genuinely reputable service that encrypts uploads and deletes them after a couple of hours has still received your file. You are trusting a policy and a promise, not a technical guarantee.
For a meme image you found online, fine, the stakes are low. For anything sensitive, a signed contract, financial records, anything with personal data, trusting a policy is the wrong security model. The right model is to not send the file anywhere at all.
The safer approach: convert locally
The security consensus has actually converged on a clear hierarchy. As one 2026 security writeup lays it out: for maximum safety, use desktop software or browser-based converters that process locally; for ordinary convenience with non-sensitive files, reputable server-based converters are acceptable if you understand their retention; and for sensitive documents, you should never use a server-based online converter at all.
The common thread in the safe options is that the file never leaves your device. Local conversion sidesteps both risks at once. There is no upload, so there is no copy of your file on a stranger’s server and no exposure in transit. And because you are not downloading a processed file back from an unknown server, the malware-injection path the FBI warned about does not exist.
Modern browsers can do this. They are capable of heavy file operations entirely on your own machine, using built-in browser capabilities, with nothing sent anywhere. The conversion happens in front of you, on your hardware, and the file stays put.
What to do
For anything you would not email to a stranger, stop uploading it to convert it. Use a tool that processes the file locally so the document never leaves your device. You get the conversion without either risk the FBI warning was about, no server holding your data and no mystery download carrying a payload.
File Forge is a browser extension that converts files entirely on your own machine. Nothing uploads, nothing is sent to a server, and the file you started with never leaves your device, which is exactly the local-processing approach the security guidance points to.
This article covers a security topic for general awareness. If you believe a device has already been compromised by a malicious download, treat it as a security incident and consult a qualified professional.