I Tested 18 Online PDF and Image Tools: 12 Uploaded My File

TL;DR: I added the same test PDF and the same test photo to 18 popular free online PDF and image tools and logged every network request. 12 of the 18 sent the file to a server. All 8 PDF tools I could measure uploaded it, and 10 of the 12 uploads started the moment the file was chosen, before I pressed any button. The full table, method and raw CSV are in the upload test write-up on editpdf.tools.

Why did I run this test?

I build editpdf.tools, a set of PDF and image tools that run in the browser. People often ask "does this site upload my file?", and most tool pages do not say it clearly. So I measured it instead of guessing.

How did I test it?

• Same files everywhere: a one-page PDF of 150,608 bytes and a 2400 x 1800 px JPG of 326,154 bytes. Both were generated for the test, with no personal data.
• Same starting point: a fresh tab in a Chromium-based browser on Windows, not logged in, cookie banners left unanswered.
• Scripted: a small script put the file into each tool's own file picker and logged every XHR, fetch and sendBeacon call with its URL and body size. I confirmed each upload a second time with the browser's Resource Timing list.
• Public address check: where the result had its own URL, I opened it in a fresh tab with no cookies.

The core of the logger is a few lines that wrap the browser's request functions:

const log = [];
const size = b => b?.size ?? b?.byteLength ?? (typeof b === 'string' ? b.length : 0);
const origFetch = window.fetch;
window.fetch = (input, init) => {
  log.push(['fetch', String(input.url || input), size(init?.body)]);
  return origFetch(input, init);
};

What did I find?

Finding	Result
Tools that sent the test file to a server	12 of 18
PDF tools (that I could measure) that uploaded	8 of 8
Image tools that uploaded	4 of 10
Uploads that started when the file was chosen	10 of 12
Results reachable at a public address with no login	2

The two public addresses both returned "page not found" when I checked again about 24 hours later.

Is uploading bad?

Not by itself. Many services delete files after a set time, and the write-up quotes each tool's own deletion policy next to its result, from 20 minutes to 48 hours. The point is simpler: you should know where your file goes before you add an ID card, a bank statement or a contract.

How did my own tools do?

I ran my own Compress PDF and Compress Image to KB the same way, as a control. After the file was added, no request was larger than 1 KB, only analytics and ad-quality pings. One honest note: Edit PDF, my paid tool, does upload the file for processing, and its page says so.

How can you check any tool yourself?

1. Open the tool and press F12 (or right-click and choose Inspect).
2. Open the Network tab and clear the list.
3. Add a small test file you do not mind sharing.
4. Look for a new POST or PUT request close to your file's size. If you see one, the file left your device.

What are the limits?

It is one browser on one day (4 November 2026). Any site can change how it works after that. The test shows that a file was sent and where, not what happens on the server afterwards.

FAQ

Do online PDF tools upload your files? Most of the ones I tested do. All 8 measurable PDF tools uploaded the test file.

Which image tools kept the file in the browser? 6 of the 10 image tools processed it locally.

Can I reuse the data? Yes. The raw CSV is linked on the research page under CC BY 4.0.

Will you test again? Yes, every six months, with the new date on the same page.

Comments

[Chandan Singh]

Happy to share the logger script I used if anyone wants to run the same test on other tools. If you maintain one of these tools and something changed, tell me and I will re-test.