Free browser tool

Merge PDF

Add several PDFs, check their page counts, arrange them in the exact order you need, and create one combined download.

Processed on your device

File inspection and merging use pdf-lib in module workers. The selected PDFs remain on your device and are released when you remove them, close the page, or finish the task.

Add PDFs to mergeUp to 20 files, 50 MB each and 150 MB combined

Simple workflow

How it works

Add your PDFs

Choose multiple valid PDF files within the file-count and combined-size limits.

Check the list

Review filenames, file sizes, page counts, and the combined input size.

Arrange the order

Drag rows or use move buttons. The displayed order becomes the output order.

Merge and download

A worker copies the pages into one new PDF and sends it to your downloads.

Compatibility

Supported formats

Input: multiple PDF files

Up to 20 PDFs, no more than 50 MB per file and 150 MB combined, with valid PDF signatures.

Output: one PDF

A combined application/pdf file whose pages follow the displayed source-file order.

Honest expectations

Known limitations

Password-protected or encrypted PDFs are not supported.
Digital signatures will not remain valid after document pages are copied into a new file.
Bookmarks, attachments, forms, scripts, and some annotations may be changed or omitted.
Duplicate filenames are allowed, so identify files by size and order as well as name.
A 150 MB input can require substantially more than 150 MB of working memory.
Large merges may fail in memory-constrained mobile browsers.

Document privacy

What stays in your browser

The browser reads each selected PDF into memory for validation, page counting, and merging. The files are not uploaded, and no selected PDF binary is written to IndexedDB.

Generated output exists as a temporary browser object long enough to trigger your download. Your browser and operating system control the final downloaded file.

Questions answered

Frequently asked questions

Are the PDFs uploaded while they are merged?

No. pdf-lib opens and combines the selected files inside module workers running on your device. No merge API or document storage server is involved.

How many PDF files can I merge?

You can select up to 20 files. Each file can be up to 50 MB, and the combined input must not exceed 150 MB. These are browser reliability limits rather than upload limits.

How do I control the page order?

The output follows the displayed file order. Drag rows, or use the accessible move up and move down buttons, before starting the merge.

Can I merge password-protected PDFs?

No. Remove the password in software you trust, save an unprotected copy, and add that copy to the list.

Will bookmarks and forms still work?

Page appearance is usually preserved, but advanced structures such as bookmarks, forms, attachments, digital signatures, and document-level scripts may not survive the merge.

Keep working

Practical reading