Merge PDF without uploading: what happens to your file

The page tools run in your browser. When you use Merge PDF, the page reads your files from your disk, copies their pages into a new document with a PDF library (pdf-lib) and hands you the result as a download. None of that needs a server, so nothing is sent to one. The PDF is read and rebuilt on your device.

That's different from the AI jobs in the same app, which do upload the file to a model provider. The difference matters, so there's a section on it below. Merging and the page tools use no Gems.

You don't have to take our word for any of this. The next section shows how to look for yourself.

Every modern browser lets you watch what a page sends. It takes about a minute.

• Open the page with the merge tool, then open the browser's developer tools (F12, or Ctrl+Shift+I on Windows and Linux, Cmd+Option+I on a Mac).
• Click the Network tab and clear the list, so you start from empty.
• Add your files and run the merge, then download the result.
• Look through the new entries for any request that carries your file. Sort by size, or look for a POST request. You're checking for a body about as large as your PDFs, or a request that includes a file name.

You won't find one. Anything that appears will be small and unrelated to your documents. Page scripts and styles are normally loaded before you add anything, so focus on what shows up after.

We also read the code: the page tools make no network calls. The Network tab is how you confirm that on your own machine, with your own file.

Say you have three PDFs for a visa application: a bank statement, a letter and a booking confirmation. That's an example, but the flow is the same for any set.

• Open the Combine tool. The web app may ask you to sign in first (email or Google).
• Add the files. You can pick several at once.
• Put them in the order you want them to appear.
• Remove anything you added by mistake.
• Download the merged PDF. It arrives as one file.

Before sending the result anywhere, scroll through it once. Check that the order is right and that no page is rotated the wrong way. If one is, the Pages tool can rotate it. Page tiles there show the page number and rotation rather than thumbnails, so you'll want to know which page you're after.

Yes to all three. Besides PDFs, Combine takes JPG and PNG images and adds them as pages. A photo of a signed form, a receipt or an ID copy can sit between two PDFs in the final document.

You can reorder files before you download, and remove any you don't need. For single pages inside one PDF, open Split PDF, where you can select pages (also by range, such as "1-3, 5"), rotate, delete or move them, and then save or extract the selection.

One pitfall. An image added as a page stays an image. It has no text layer, so if you later run an AI job such as chat or summarise on the merged file, the model can read the PDF pages but not the photo. The tool has no OCR.

Each file can be up to 50 MB. The cap exists because the browser holds everything in memory while it works. A merge of many large files can slow down or fail. If it does, merge in smaller batches, or cut big files down first with Split PDF.

The page tools are deliberately small. They won't:

• Compress. A merged file is roughly as large as its parts added together.
• Edit text. You can't fix a typo or change a number inside a page.
• Remove passwords. If a PDF is protected, open it with its password in a viewer you control, re-save a copy without it, then add the copy.
• Read scans. There's no OCR, so image pages stay pictures.

If you need one of those, you'll need other software. We'd rather say so than leave you guessing.

The AI jobs do. Chat, summarise, translate, tables, explain, study notes and compare send the PDF to the model provider you picked, and the whole file goes again with every message. That's how the model can read it at all. Page ranges help a little: the tool cuts the range out on your device first, so only those pages leave it.

For a document you'd rather keep on your machine, you have clear choices.

• Don't run an AI job on it. Merge, split and reorder with the page tools, which upload nothing, and read the file yourself.
• Cut the sensitive pages out with Split PDF first, then send only what remains.
• Make the decision per file. If you wouldn't email it to an outside service, don't send it to a model.

For how an AI session works, see how to chat with a PDF.

Opening the web app may ask you to sign in with email or Google before the tool appears. That's the app's front door, not part of the merge itself, which still happens in your browser.

Merging uses no Gems. Gems are charged for the AI jobs, by model tier, with the cost shown before you run each one. The page tools are free to use. New accounts start with 30 Gems, and pricing lists the packs and plans if you ever want to run AI jobs on the merged file.