KEMI Tools

Merge PDF

Combine several PDFs into one, in exactly the order you want. Drag files into order, pick only the pages you need, or mix and rotate pages individually. Everything happens inside this browser, so certificates, contracts and design drawings never leave your device. No sign-up, no watermark, no limits.

Drop the PDFs you want to merge

Select several at once · or click to browse

🔒 Files are processed only inside your browser on this device and are never uploaded. The site records an anonymous "tool used once" count — never file names or contents.

How to use

Drop the PDFs you want to combine into the box above (or click to choose). You can add more later.
Drag files into order — on phones use the ↑↓ buttons. “Sort by name” lines up 01, 02 … in one tap.
To include only part of a file, type a range like 1-3, 5 in its Pages box. Leave it empty for all pages.
To interleave pages between files, or rotate/drop single pages, click “Show all pages” and edit page by page.
Choose an output name and press “Merge & download” — the combined PDF downloads immediately.

What actually happens when PDFs are merged

A PDF looks like a stack of sheets, but inside it's a collection of objects. Each page is a page object with its size and rotation; what it draws is defined by a content stream — drawing commands that place text in a given font at given coordinates, plus lines, shapes and images. Fonts and photos are separate objects that several pages can share, and the cross-reference table at the end indexes where every object lives in the file.

This tool doesn't re-render your pages as pictures. It copies the page objects — together with the fonts, images and content streams they reference — into a new document (pdf-lib's copyPages). That's why the merged file stays searchable and copyable, and why vector drawings such as schematics stay crisp at any zoom. There's no quality loss and no needless growth in file size.

If the originals are scans, though, they are already photos, so the merged file is a photo PDF too. Use an OCR program if you need searchable text.

When it helps — submissions, quote and drawing packs

Government offices, schools and employers often ask for “a single PDF”. Put the application form, certificates and statements in the required order and save them as one file. Prefixing names with 01_, 02_ and pressing “Sort by name” is the fastest way to get the order right.

In electronics and manufacturing you often need to send schematics, assembly drawings, a BOM and test reports together. One merged PDF means nothing gets lost and the email stays tidy. Page mode lets you slip a cover sheet in front or straighten a sideways drawing.

How this differs from upload-based PDF sites

Many PDF websites send your files to their own company, merge them there and send the result back. They usually promise to delete files later, but uploading ID documents, contracts or unreleased designs to someone else's company can be a real concern.

Here the processing code runs entirely in your browser, reading and writing the PDF in your device's memory. File contents never cross the network — once you've added files you can even go offline and merging still works. The site only records an anonymous “tool used once” count.

Size and speed tips

Speed depends on your device. Dozens of typical documents and hundreds of pages finish in seconds. Sources are read one at a time to save memory, but the merged file is built in memory, so jobs totalling several hundred MB are safer on a computer than a phone. If you hit a memory error, merge in two batches and then merge the results.

The merged size is roughly the sum of the inputs (shared fonts are stored once per source file). If the result is too big, rescan at a lower resolution or run image-heavy documents through a PDF compressor.

Privacy

The PDFs you choose are read and merged only in this browser's memory and are never stored. Closing the tab clears them. The site records only an anonymous “tool used once” count — never file names, contents or page counts. Ads on this page have no access to your files.

FAQ

Are my files really not uploaded?

Correct. Merging is done by JavaScript (pdf-lib and pdf.js) running in your browser's memory. Open your browser's developer tools, watch the Network tab while you merge, and you'll see no file is sent.

Is the merged PDF still searchable?

If the originals were searchable, yes — pages aren't converted to images; content streams and fonts are copied as-is. Scanned pages are photos, so they were never searchable.

It says the PDF is protected and can't be merged.

PDFs with an open password or permission restrictions are encrypted and can't be edited here. If viewing and printing are allowed, open it in Chrome or Edge and use Print → Save as PDF to get an unrestricted copy (text is usually preserved). Only do this if you have the right to use the document.

Are bookmarks and form fields kept?

Page content is copied exactly, but document-level bookmarks (outline), fillable form fields and internal links to other pages may be dropped or stop working. Finish filling forms before merging.

Is there a limit on files or size?

No artificial limit. Everything runs in your device's memory, though, so merging hundreds of MB on a phone may crash the tab. Use a computer for big jobs, or merge in batches.

Does it work on phones?

Yes — Chrome and Samsung Internet on Android, Safari on iPhone. Use the ↑↓ buttons instead of dragging to reorder.