Merge PDF

What is Merge PDF?

Merge PDF is a free online PDF combiner that joins two or more PDF files into a single document right in your browser. Students, freelancers, and office workers use it to combine scanned pages, invoices, contracts, statements, and report chapters into one downloadable file. Because every PDF is processed locally with the pdf-lib library, you can reorder files before merging, preview the first page of each, and export a single merged.pdf without ever uploading sensitive documents. It is the tool to reach for whenever you need to combine, append, or stitch PDFs together quickly. You can also drag rows to reorder them, set a page range per file (like 1-3,5) so only selected pages are merged, interleave pages from two files, and preview the merged result with its total page count and file size before downloading.

How to use Merge PDF

1. Drag your PDF files onto the dropzone, or click it to browse and select several PDFs at once.
2. Reorder the queue by dragging a row's grip handle or using the up/down arrows; click a first-page thumbnail to zoom in, or the X button to remove a file.
3. In each file's Pages field, type a range like 1-3,5 to merge only those pages, or leave it blank to include all pages.
4. Open the gear Settings to turn on Interleave — which alternates one page from each file in turn (ideal for two files) — or Replace list when adding new files.
5. Review the merged preview thumbnails plus the output page count and size, then click Merge to build and download merged.pdf.
6. Use Clear to empty the queue and start over.

Examples

Frequently asked questions

Are my PDF files uploaded to a server?

No. Everything runs 100% client-side in your browser using the pdf-lib library. Your files never leave your device and are never uploaded, which is why it is safe for contracts, statements, and other sensitive documents.

How many PDFs can I merge at once?

You can add as many PDF files as you like, but the Merge button only becomes active once at least two files are queued. All pages from every file are copied into one combined document.

Can I change the order of the files before merging?

Yes. Each file in the list has up and down arrow buttons so you can reorder it, plus an X button to remove it. Files are merged in the exact order shown in the list.

Why won't my file merge or why do I get an error?

The tool only accepts PDF files (.pdf); other file types are ignored when added. If you see 'Could not merge these PDFs,' one of the files may be corrupted or password-protected, which can prevent it from being combined.

What is the merged file named and what format is it?

The output is a standard PDF saved as merged.pdf. The merge keeps every page from each input file in the chosen order.

Can I merge only certain pages from a file?

Yes. Each file has a Pages field where you can enter a range such as 1-3,5 to include only those pages; leave it blank to merge the whole file. Values beyond a file's page count are clamped automatically.

What does the Interleave option do?

With Interleave on, the tool alternates pages — page 1 of file A, page 1 of file B, page 2 of file A, and so on — instead of appending each file after the previous one. It works best when merging two files, using each file's selected page range.