How to check that robinpdf never uploads your files
Every browser-based PDF tool says your files stay on your device. The claim costs nothing to make, so it is worth nothing on its own. Here is how to check mine in under a minute — and the same three tests work on any other site, including the ones I compete with.
Test 1 — Turn off your Wi-Fi
Open any tool on this site and wait for the page to finish loading. Now disconnect from the internet: turn off Wi-Fi, or pull the cable. Then use the tool as normal — pick your files, run it, download the result.
It still works. A site that uploaded your document to a server could not possibly do that. This is the whole test, and it takes about thirty seconds.
Test 2 — Watch the network tab
Press F12 to open your browser's developer tools and switch to the Network tab. Leave it open while you process a file. You will see the page's own assets load, and you will not see your document go anywhere: no upload request, no POST carrying the file, nothing.
This is the test to run on any site that claims local processing. If you see your file in a request body, the claim was false.
Test 3 — Read the security policy
Browsers let a site declare, in a header, which outside servers it is allowed to talk to at all. Mine allows exactly one, and it is not a place your files could go — it is Cloudflare's cookieless visit counter. You can read it yourself in the Network tab: click the first request and look at the response header called Content-Security-Policy.
There are no advertising or tracking domains in that list. There is no ad script on the site at all.
What I measured
robinpdf has an automated test that loads a tool in a real browser, cuts the network at the browser level, and then processes a file. Of the 13 tools it covers, 11 complete the job with the network down:
- merge pdf
- split pdf
- rotate pdf
- crop pdf
- pdf to jpg
- grayscale pdf
- pages per sheet
- pdf to text
- add page numbers
- edit pdf metadata
- pdf to word
Where it does not hold
I would rather tell you this than have you find it: two things need the network the first time you use them.
- OCR and the password tools download a processing engine on first use — tesseract for text recognition, a WebAssembly build of qpdf for encryption. Together those are several megabytes, which is why they are not loaded for everyone who opens the page. That is program code coming down to your browser. It is never your file going up. PDF to Word is on the list above because a text PDF needs no OCR; a scanned one does, and then it needs that first download too.
- Compressing a very small PDF does nothing at all: the tool checks whether it can actually make the file smaller and declines rather than handing you a worse copy. That is a refusal, not a failure.
Why build it this way
Because "we delete your file within a few hours" is a promise, and an architecture that never receives the file is a fact. For a holiday photo the difference does not matter. For a contract, a payslip, a medical report or a scan of your ID, it is the only thing that matters. If you handle documents you are not allowed to upload, you should not have to take anyone's word for it — including mine.