Online tools are convenient, but you're uploading your documents to someone else's server. That's fine for most files — and not fine for a few — so it's worth understanding what good tools do.
What to look for
Encryption in transit (HTTPS), automatic deletion of your files shortly after processing, and no requirement to create an account just to run a quick tool. EditJ encrypts uploads, auto-deletes both the upload and the result about two hours after processing, and lets you use the core tools without signing up.
When to be cautious
For highly sensitive documents — legal, medical, or anything with personal identifiers — prefer tools that delete promptly and never ask you to keep files on their servers. And always remove a password from a PDF you own using the Unlock tool, never a third-party 'cracker'.