Do UtilNest tools upload your files? How browser-only tools work

Most UtilNest tools do the work inside your browser. Your file is read by the page on your computer or phone, the result is made there, and for those tools your file is never sent to our servers. You can check this yourself with the browser's network tab, and this post shows how.

What "runs in your browser" means

A web page is code your browser downloads and runs. For a browser-only tool, that code includes everything needed to do the job: the PDF library, the image resizer, or the AI model. When you pick a file, the page reads it from your device, processes it in memory and offers the result as a download. The file is never sent anywhere.

Because nothing is uploaded, these tools have no file-size limit of their own. The limit is your device's memory. A large file on an old phone can be slow or run out of memory; the same file on a laptop is usually fine.

Most of these tools take up to five files at a time, with or without an account. Merge PDF is one job, so it takes up to 100 files into one PDF.

Which tools stay on your device

These tools run entirely in the browser:

• Compress PDF: re-encodes the photos inside the PDF at a lower resolution. Text and fonts are not touched. A PDF with only text will not get smaller.
• Merge PDF: copies pages from several PDFs into one, in the order you set.
• Split PDF: one file per page, per range you type, or every N pages.
• Unlock PDF: removes a password you already know. It does not guess or crack passwords. How to unlock a PDF you own walks through it.
• Resize image: by percentage, width, height or to fit a box, keeping the proportions.
• Remove text from image: you paint over the text and an AI model running on your device fills the area. The model (28 MB) and its runtime (26 MB) are downloaded to your browser the first time you run it; your picture is not sent anywhere.
• Word counter: the text stays in the tab.

How to check it yourself

You don't have to take our word for it. Every desktop browser can show you each request a page makes.

1. Open the tool page, for example Merge PDF.
2. Open the developer tools: press F12 (or Cmd+Option+I on a Mac) and choose the Network tab.
3. Click the clear button so the list is empty.
4. Add your files and run the tool.
5. Look at the list. The first time you run a tool you will see the tool code being downloaded, and for the AI tools also the model and its runtime, which is more than 50 MB for Remove text from image. Those are downloads to your device. You will not see a request that sends your file: no upload whose size matches your file.

A simpler test: run the tool once with any file, after the page and any model have loaded. Then turn off Wi-Fi and run it again in the same tab, without reloading. A browser-only tool still works. (Reloading the page while offline does not work, because the page itself has to be downloaded.)

What does upload, and how you can tell

Some jobs can't run well in a browser, so they run on our servers. Those pages say so before you start.

• Office files to PDF, such as Excel to PDF, upload the file to private storage, convert it on a server and give you a download link that expires after 10 minutes.
• AI writing tools, such as the AI translator, send your text to an AI model. They need an account and use credits.

The plan file-size limits apply only to these uploaded jobs: 10 MB without an account, 25 MB on the free plan, 100 MB on Plus and 250 MB on Pro. They never apply to the browser-only tools above.

Summary

Tool	Where it runs	File sent to a server?	Size limit
Compress, merge, split, unlock PDF	Your browser	No	Your device's memory
Resize image, remove text from image	Your browser	No	Your device's memory
Word counter	Your browser	No	Your device's memory
Office files to PDF	Our servers	Yes, and the page says so	10 to 250 MB by plan
AI translator	Our servers	Yes, the text	3,000 words per run

When in doubt, open the network tab and look. It takes two minutes and shows you exactly what leaves your device.