PDF is an incredibly popular file format for sharing documents, used by individuals and organizations alike. This means that every so often, we find ourselves in situations where we need access to a PDF converter or editor.
Whether it’s for compressing a PDF to meet a website’s upload size limit or converting a Word document to PDF for sharing, PDF tools are a crucial part of the process. This has resulted in a flood of online PDF converters and editors that can do most things you need with a PDF in just a couple of clicks. These are some handy web apps, and more often than not, they do a good job. Still, I stay as far away from these online PDF tools as I can. Here’s why you should, too.
Your PDF Files Are at the Mercy of the PDF Converter
When you upload your documents to an online PDF tool, you are giving the website access to them. Although most websites that offer PDF tools claim to delete your uploaded documents in a matter of hours, there is no guarantee that it will happen. As soon as your documents reach the PDF converter, they are at the mercy of the company or webmaster running that website.
According to Cybernews, two online PDF makers were found to be leaking thousands of user-uploaded documents in July 2024. These documents included sensitive items such as passports, driving licenses, contracts, and certificates. Such sensitive documents are a gold mine for identity thieves. All of this happened because the operators of these web apps were careless in handling the documents being entrusted to them and left the documents accessible to anyone savvy enough to find their cloud server.
Even if the PDF converter deletes your uploaded documents within the stipulated timeframe, your documents remain at risk between the time you upload them and when they are deleted if the service doesn’t store them properly.
You Risk Your Data and Device Security
Beyond the privacy of your documents, using random online PDF converters also poses a significant security risk. Like other file formats, PDFs can be armed with malicious code. So, when you download your converted or edited PDF from an online converter, you don’t know what else may be included.
The FBI’s Denver office issued a warning in March 2025 about precisely this issue. It claimed that some online document converters were inserting malware into converted and edited files, including PDFs. The malware would steal personal information, banking details, passwords, crypto wallet details, and more.
The FBI isn’t the only one noticing this trend among cybercriminals. In April 2025, cybersecurity company CloudSEK released a research report detailing how fake PDF converters were transmitting malware and stealing from unsuspecting people. What’s more alarming is that these are sophisticated cybercriminals. One of the fake PDF converters created by these criminals mimicked the popular PDF converter “PDF Candy” and had a genuine-looking URL and page design.
This makes it pretty clear that you are not just risking your documents when using online PDF converters, but also your devices and your digital life at large.
Using web apps may be justified if there weren’t good offline PDF tools, but that’s not the case. There is an excellent selection of offline PDF converters and editors that perform all the processing on your device, and some of these are even open-source, allowing the community to review their code and ensure there are no hidden surprises. So, there is simply no reason for anyone to rely on online tools unless, of course, you are relying on a trusted service, such as the one offered by Adobe.
If you’re looking for a reliable PDF manipulation tool, PDF24 Creator is an excellent option. It’s available for Windows and includes a bunch of features, including the ability to convert, merge, compress, and sign PDFs. It does everything locally and is available through the Microsoft Store, as well as on the company’s website. App store availability is particularly helpful if you want to avoid landing on a clone website, such as the one created by cybercriminals for PDF Candy.
For open-source enthusiasts and folks using macOS or Linux, Stirling PDF is a great choice. While many savvy individuals prefer to host it on their own server, it has clients for all three major platforms that essentially package the web application and a local server into one neat, native app for a hassle-free installation. It offers a comprehensive set of PDF manipulation tools. If you don’t need as many features, PDFsam Basic and PDF Arranger are also worth considering.
Unfortunately, cybercriminals are lurking everywhere, hoping that you will make a mistake. As a result, it’s crucial that you avoid random online tools for everything, including document conversion, and stick to reputable ones. If you can use an offline option, that’s even better. Moreover, it’s always a good idea to practice cyber hygiene for a safer digital life.
