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.
UnboundPDF is a free suite of 53 PDF and image tools that run entirely in your browser — merge, split, compress, edit text, OCR in 126 languages, redact, sign, convert and archive to PDF/A. Your document is read and written by the page on your own device; there is no document-upload endpoint in the core tools, no account, no watermark and no daily cap. Every result can be checked — with the Network tab, or with the Document Passport the Workspace writes for a chain of steps.
Is Stirling PDF safe?
Short answer: yes, for most documents. Stirling PDF is open-source software you host yourself. Files stay on infrastructure you control, because you are the one running it.
Self-hosting genuinely answers the transmission question — if you run the server, your files stay yours. The real comparison here is effort: a Docker deployment you maintain versus a browser tab that requires nothing. Both keep the document under your control.
The actual difference
| Feature | Stirling PDF | UnboundPDF |
|---|---|---|
| Where the work happens | A server you run yourself | Your browser |
| Is the file transmitted? | Only to your own server | 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 |
Where each one fits
UnboundPDF is the right choice when you want Stirling's privacy without running a server: nothing to self-host, nothing to update, the same no-upload processing on any device, and the Workspace for chained jobs with a record. Stirling PDF fits a technical user who wants to self-host a PDF service on their own infrastructure.
Verify it in one minute
The same verification applies to both: open DevTools → Network and watch where your file goes — to your own server in Stirling's case, nowhere in ours. The Privacy Lab shows how to read what you see.
Try it on a copy first
Use a file you do not care about, watch the Network tab, then decide.