Most free online tools work the same way: you upload your file, a server somewhere processes it, and you download the result. That middle step is the problem. Your file now exists on a machine you do not control, and you have only a promise about what happens to it next.
Thirty-four of the tools on this site do not work that way. The file never leaves your computer.
The claim, plainly: for the 38 tools listed below, nothing you drop in, type in, or paste in is sent anywhere. The processing happens in your browser, on your device. There is no upload, so there is no copy on our server — because there is no server step at all.
You do not have to take our word for any of that, which is the point of this page.
How to check we are telling the truth
This takes about thirty seconds and works on any website, not just ours. Do it to us. Then do it to whatever tool you were using before.
- Open any tool from the list below. The image compressor is a good one to test, because an image is large enough that an upload would be obvious.
- Press F12 to open your browser’s developer tools, then click the
Networktab. On a Mac it isCmd + Option + I. - Clear the log. There is a circle-with-a-line icon, or press
Ctrl + L. You want a clean slate before you start. - Use the tool. Drop in a photo, set a target size, run the compression, download the result.
- Read the network log. You are looking for any outbound request carrying your file — usually a
POST, or afetchto a domain that is not ours. There will not be one. You will still see the page’s own assets and a couple of requests that build the navigation menu — every website makes those, and they fire before you touch the tool. What you will not see is anything sized like your file.
That is the quick version. The full method — including an even simpler offline test, what the results mean, and what the check cannot prove — is in how to tell if a website uploads your files. It works on any tool, not just ours.
Why this matters more than it used to
In March 2025 the FBI’s Denver Field Office issued a public warning about free online file converter tools. The scam works because the tool does exactly what it advertises — your file converts, you download it, nothing looks wrong. Meanwhile the converted file carries malware, and the site has scraped the original for whatever it contained.
The FBI listed what was being harvested: Social Security numbers, dates of birth, phone numbers, banking details, cryptocurrency information, email addresses and passwords. The warning was covered by BleepingComputer, Malwarebytes, Forbes and CSO Online.
Think about what people actually put through these tools. Passport scans for a visa application. A payslip for a rental deposit. Medical paperwork. A signed contract. An ID photo resized to fit a government portal’s 50KB limit.
Client-side processing does not make that risk smaller. It removes the category. If the file never leaves your device, there is no server copy to breach, subpoena, retain past its promised deletion date, or sell.
The 38 tools this applies to
Image tools 13
Calculators 6
Utilities 6
Text tools 3
Developer tools 3
What “client-side” actually means
Your browser is a capable computer in its own right. It can read a file from disk, decode a JPEG, resize it, re-encode it at a target quality, and hand it back to you as a download — without any of that data crossing a network.
The image tools use the browser’s own canvas engine for exactly this. The PDF tools assemble and parse documents in memory. The calculators and text tools are arithmetic and string handling, which never needed a server. The clustering tool compares the words in your keyword list against each other locally.
None of this is clever. It is simply the option most tool sites do not take, because a server-side pipeline is easier to build, easier to monetise, and easier to instrument.
The honest trade-offs
| What you get | What it costs |
|---|---|
| Your file is never transmitted, so it cannot be intercepted or retained | Very large files are limited by your device’s memory rather than a server’s |
| Works offline once the page has loaded | The first load is slightly heavier, because the logic ships to you |
| No account, no queue, no rate limit — there is nothing to meter | Older phones will be slower on heavy image batches |
| Nothing to breach, because nothing is stored | No processing history, because we genuinely do not have one |
Frequently asked questions
How do I know this is not just marketing?
Run the network-tab check above. It takes thirty seconds and it is not something we can influence — you are reading your own browser’s record of what happened. That is the whole reason this page leads with the method rather than the promise.
Do you log anything at all?
The site runs standard web analytics on page visits, the same as most sites. That records that a page was opened. It does not and cannot record the contents of a file you processed, because that content never reaches us.
Does this work offline?
Once a tool page has loaded, yes for most of them. Disconnect your network and the compressor will still compress. It is a decent second way of proving the point to yourself.
Why give this away free?
There is no server cost to recover. The tools sit alongside guides and reviews, some of which carry affiliate links, and that is disclosed. The tools themselves have no upsell because there is nothing to upsell.
Can I use these for client or work files?
That is a question for your own policies, but the architecture is the part people usually need to check. Nothing is transmitted, so there is no third-party processor involved in the step. Verify it yourself first — for anything sensitive, you should be doing that with every tool you use, not just this one.
What about the tools not on this list?
Treat them as ordinary web tools until stated otherwise. When each has been verified, it will be added here with the same standard of proof.