I wonder if the tools are also vetted for security. IIRC there was some supply chain attack that had to do with similar no-signup tools injecting SEO scam code (https://news.ycombinator.com/item?id=27427330)
Good point. I'm very wary of submitting anything security sensitive to an unfamiliar web site, especially one I don't have a business relationship with.
If you have a business relationship with them (i.e. give them money), they're less likely to do something bad with your data since it may cause you to stop giving them money.
That's why I won't use tools like an online PDF tool when I'm dealing with PDFs that contain sensitive information.
That wouldn't do any good; these are network services, so they could always add attack code after the vetting, or perform a de-anonymization attack (trivial if you're not using TOR, potentially jury-riggable (eg based on what files you use them on) even if you are) and send it only to targeted visitors.
