Do KitWren’s tools upload my files?

333 of the 348 tools, including every PDF, image and text tool, work in your browser and don’t upload anything. The 15 exceptions — mainly AI tools — say so on their pages.

How can I check whether a website uploads my files?

Open the browser’s developer tools (F12), go to the Network tab, use the tool, and look for a request about the size of your file.

Does the site collect anything at all?

Like most websites, pages load code, fonts and ads, and analytics runs only if you consent. Your files and the content you enter in in-browser tools are not sent.

Do in-browser tools work offline?

They need the internet to load the page. Some keep working if the connection drops after loading, but that isn’t guaranteed for every tool.

Free tools

Online Tools That Never Upload Your Files

Updated 27 September 2026 · 4 min read

When you use a typical online tool, your file makes a round trip: it’s uploaded to a company’s server, processed there, and sent back. KitWren takes a different approach for the vast majority of its tools — 333 of 348 — which run entirely inside your web browser. The file you choose never leaves your computer or phone. Here’s how that works, which tools it covers, the few that are different, and how to check any website for yourself.

Open the free PDF Compressor

What “in the browser” means

Modern browsers can run serious software. When you open an in-browser tool, the page downloads the program — for example a PDF engine or an image encoder — and runs it on your own device. When you choose a file, the browser hands it to that program inside the tab. The result is created on your device and downloaded from memory. At no point does the file travel over the internet.

	Server-based tool	In-browser tool
Your file is sent over the internet	Yes	No
A copy may exist on someone else’s computer	Possibly, until deleted	No
Waiting for uploads and downloads	Yes	No
Works with very large jobs on a slow device	Often better	Depends on your device

Which KitWren tools run in your browser

All 30 PDF tools — merge, compress, edit, sign, redact, convert, OCR and more.
All 25 image tools — compress, resize, convert HEIC, remove backgrounds, passport photos, EXIF removal.
Text tools — the Word Counter, Character Counter, Case Converter and others. Your text isn’t saved or sent.
Calculators and converters — mortgage, tax, GST, 123 unit converters and more. The numbers you enter stay on your device.
Generators — QR codes, passwords, invoices.

The exceptions, stated plainly

Fifteen tools need a server because of what they do, and their pages say so:

AI writing tools (such as the AI summariser, rewriter and translator) send the text you enter to an AI service to generate a response.
The website screenshot and HTTP status tools have to visit the web address you give them.

A few in-browser tools also fetch reference data — the currency converter downloads exchange rates, and OCR downloads language data the first time you use a language — but your own file or numbers are not sent.

Check it yourself in 30 seconds

You can verify any website’s claim, not just ours:

On a computer, open the tool in Chrome, Edge or Firefox.
Press F12 (or right-click the page → Inspect) and choose the Network tab.
Click the 🚫 “clear” button so the list is empty.
Use the tool on a file.
Look at the new entries. An upload shows up as a request with a size roughly equal to your file (often a POST request). With an in-browser tool you’ll see nothing like that — at most small requests for page code, fonts or ads.

What in-browser tools don’t protect against

What happens after you download. The finished file is yours to protect — on a shared computer, delete it from Downloads when you’re done.
Your device itself. Malware or an untrusted browser extension can see anything you do, on any website.
Sharing. Once you email a document, its safety depends on the recipient.

Everyday privacy habits

Prefer in-browser tools for sensitive files — ID documents, payslips, medical letters, contracts.
Strip photo metadata before posting: phone photos can include GPS location. Use the EXIF Remover.
Redact properly with Redact PDF, not by drawing boxes in an ordinary editor.
Send only what’s needed — extract the relevant pages instead of the whole statement.
Password-protect sensitive PDFs with Protect PDF and share the password separately.

In-browser processing also means no account and no stored history: there’s nothing to log in to, so there’s nothing to leak later. For a closer look at PDF privacy, see a private alternative to upload-based PDF sites.