Is My File Converter Safe?
Free interactive safety checker
In March 2025, the FBI warned that criminals were using fake file converters to distribute malware, ransomware, and spyware. The tools worked as advertised but secretly installed malicious software. Use this checker to evaluate whether the file converter you are using is safe.
1. Where does the file get processed?
2. Does it require creating an account?
3. Does it show ads or pop-ups?
4. What do you download after conversion?
5. Does the site use HTTPS (padlock icon)?
6. How long does the site keep your files?
7. Does it add watermarks to converted files?
8. Are there file size or usage limits?
9. Does the site have a clear privacy policy?
10. Is the tool from a known, established source?
0 of 10 questions answered
Answer at least 5 questions to get a score
Popular Converter Safety Scores
We evaluated popular file converters against the same 10 criteria. Browser-based tools score highest because your files never leave your device.
| Converter | Processing | Score |
|---|---|---|
| FileToolWorksRecommended | Browser | 98/100 |
| VERT.sh | Browser | 95/100 |
| CloudConvert | Server | 72/100 |
| Convertio | Server | 68/100 |
| Zamzar | Server | 65/100 |
| iLovePDF | Server | 70/100 |
| Smallpdf | Server | 69/100 |
| FreeConvert | Server | 66/100 |
| Online-Convert | Server | 64/100 |
What Did the FBI Warn About?
In March 2025, the FBI Denver Field Office issued a public warning about free online file converters that distribute malware. The warning stated that criminals create legitimate-looking converter tools that actually install ransomware, keyloggers, or crypto miners on victims' computers.
The FBI specifically warned about tools that:
- Require downloading and installing software on your computer
- Upload your files to unknown servers
- Show aggressive ads, pop-ups, or redirects
- Request unnecessary permissions or personal information
How to Stay Safe
The safest file converters process everything in your browser. Your files never leave your device, there is nothing to install, and no data passes through third-party servers. Look for tools that explicitly state they use client-side or browser-based processing.
Read more about how browser-based processing works on our security page, or see a side-by-side privacy comparison of 15 popular file converters.
Use a Safe File Converter
FileToolWorks processes all files in your browser. No uploads, no servers, no risk. 40+ free tools for images, PDFs, videos, audio, and documents.
Frequently Asked Questions
Are free file converters safe to use?
It depends on how they work. Browser-based converters that process files locally on your device are safe because your files never leave your computer. Server-based converters carry more risk since your files pass through third-party servers. The FBI has warned about malicious converters that install malware, so always verify how a tool processes your files before using it.
What did the FBI say about file converters?
In March 2025, the FBI Denver Field Office warned that criminals were creating fake file converter websites and software that secretly installed ransomware, keyloggers, and other malware. The converters appeared to work normally, but the downloaded files or installed software contained hidden threats.
How can I tell if a file converter is safe?
Check if the tool processes files in your browser (client-side) rather than uploading them to servers. Look for HTTPS, a clear privacy policy, no required downloads, and no aggressive ads or pop-ups. Use our safety checker above to evaluate any converter against 10 security criteria.
What is a browser-based file converter?
A browser-based (client-side) file converter runs entirely in your web browser using JavaScript and WebAssembly. Your files are read, processed, and converted without ever being uploaded to a server. This is the safest type of file converter because your data never leaves your device. FileToolWorks uses this approach for all 40+ of its tools.
Is Convertio safe?
Convertio is a legitimate service, but it uploads your files to their servers for processing. They state files are deleted within 24 hours. If you are handling sensitive documents, consider using a browser-based converter instead where files never leave your device. See our FileToolWorks vs Convertio comparison for a detailed breakdown.
Is Zamzar safe?
Zamzar is a well-established converter, but it uploads files to their servers and shares data with third parties according to their privacy policy. Files are stored for up to seven days. For maximum privacy, use a tool that processes files locally in your browser. See our FileToolWorks vs Zamzar comparison for details.