Stirling PDF alternative that never uploads your file
Stirling PDF is a legitimate service, and the practical difference is architectural: it processes your file on its servers, while UnboundPDF does the work inside your browser so the document is never transmitted. If your file is confidential, that difference matters. You can verify both claims yourself in about a minute.
Updated July 2026. We do not allege anything about Stirling PDF's data handling — only the documented difference in where the work happens.
Is Stirling PDF safe?
Short answer: yes, for most documents. Stirling PDF is a real company with a published privacy policy and a large user base. Stirling PDF is open-source software you host yourself. Files stay on infrastructure you control, because you are the one running it.
The question worth asking is not whether they are trustworthy — it is whether your document should be transmitted at all. A restaurant menu, a public form: it genuinely does not matter. A signed contract, a payslip, a medical letter, anything under NDA: many people would rather it never left the machine.
The actual difference
| Stirling PDF | UnboundPDF | |
|---|---|---|
| Where the work happens | Their servers | Your browser |
| Is the file transmitted? | Yes, then deleted per their policy | No |
| Works with no internet after load | No | Yes |
| Account required | For some features | Never |
| You can verify the claim | Policy document | DevTools, in a minute |
When Stirling PDF is the better choice
Genuinely: when you can run Docker and want a self-hosted suite you fully control — for a technical user this is an excellent and genuinely private option. We would rather you pick the right tool than the one we happen to make.
Do not take our word for it either
You likely arrived here because you did not want to trust a vendor's own page — a lot of people search for exactly this and add "reddit" to the end. Fair. So here is the check that settles it for any tool, ours included: open DevTools → Network, run the operation, and watch whether your file is sent. The Privacy Lab walks through it step by step.
Try it on something harmless first
Use a file you do not care about, watch the Network tab, then decide.