Merge PDF Files Locally in Your Browser

PDFs pile up. A signed contract is three separate files, a scan arrives one page per email, and a pile of receipts needs to become one tidy expense report. The fix isn’t a paid app or a random upload site that you then have to trust with your documents. Open the Merge PDF tool and the whole job happens in your browser — no upload, no server, nothing leaving your device.

TL;DR

You can merge multiple PDFs into one file, entirely offline in the current tab.

• One file from many — combine up to 10 PDFs into a single document, in order.
• Nothing uploaded — the merge runs locally in your browser using pdf-lib; your files never leave the device.
• You control the order — move pages up or down, remove a stray file, then download the result.

Why merge PDFs

Merging is a bookkeeping move, not a technical one. The goal is to make one tidy file where there used to be many.

• Contracts and signatures — a final agreement is often a cover page plus several signed sections. One merged PDF is easier to email and harder to lose than ten attachments.
• Scanned documents — a scanner that outputs one PDF per page turns a five-page letter into five files. Merge them back into one.
• Receipts and expense reports — combine a stack of receipts into a single PDF for an expense claim or a reimbursement submission.
• Reports and chapters — stitch a cover sheet, an executive summary, and the body into one document for clean submission.

The pattern is always the same: several files that belong together become one file that reads in order. Sending ten attachments is a recipe for a confused recipient; sending one merged PDF is not.

Why local matters here

PDFs are a magnet for sensitive content. Contracts, identity documents, financial statements, tax records, and medical paperwork all travel as PDF. That is exactly the kind of material you do not want to hand to a random “free merge PDF” website — because “free” there usually means your file is uploaded to a server you don’t control, run by people you can’t see, under a privacy policy you probably didn’t read.

This tool takes the opposite approach. The merge runs entirely in your browser using pdf-lib, a JavaScript library loaded on demand. Your PDFs are read from your device, combined in the current tab, and the result is written straight back to your device. There is no upload step, no server-side processing, and no stored copy. For documents that might contain personal or confidential information, that is the whole point of doing it locally.

Merge PDFs, step by step

The Merge PDF tool does the entire job locally. Here is the workflow:

1. Add your PDF files. Drag them onto the drop zone (titled “Drop PDF files here”), or click Choose PDFs to browse. You need at least two PDFs to merge, and you can add up to 10. Each file can be up to 50 MB.
2. Put them in order. Each file in the list has Move up and Move down buttons so you can set the sequence the final PDF will follow. Use Remove to drop a file you didn’t mean to add, or Clear to start over.
3. Click Merge PDFs. The tool combines the files in order. While it works, the status reads “Merging PDFs locally…” so you know it is processing.
4. Download the result. Hit Download merged PDF to save the combined file. It is named after your first file with -merged.pdf appended.

At no point in this flow do your PDFs leave your browser.

Reordering and limits

A merge is only useful if the order is right, so the list controls matter.

• Reorder with Move up / Move down — the final PDF follows the list order top to bottom. Rearrange before you merge, because reordering after merging means starting over.
• Max 10 PDFs per batch — if you try to add more, the tool keeps the first 10 and tells you.
• Max 50 MB per file — larger files are rejected with a readable message rather than choking the browser.
• Encrypted or corrupt files fail with a clear error — pdf-lib loads with ignoreEncryption: true, but a file it genuinely cannot parse will throw a readable message instead of silently producing a broken PDF.

There is no per-page limit beyond the overall file size — a single large PDF with many pages merges the same way a small one does.

What it does not do

This tool merges PDFs and nothing else. A few things it deliberately leaves to other tools:

• No page-level editing. You can’t delete individual pages or split a PDF here — use Remove PDF Pages for that.
• No compression. Merging preserves each file’s pages as-is, so the combined size is roughly the sum of the inputs. To shrink the result, use Compress PDF.
• No image-to-PDF conversion. To combine JPG, PNG, or WebP images into a PDF first, use Image to PDF — then merge that PDF with the rest here.
• Merge preserves pages as-is. Forms, bookmarks, and internal links from the source files may not carry over into the combined document; the page content itself is kept intact.

FAQ

Are my PDFs uploaded anywhere?

No. The merge runs fully in your browser using pdf-lib. Your files are read from your device, combined in the current tab, and the result is written straight back to your device. There is no upload step, no server-side processing, and no stored copy. That is the entire reason this tool exists instead of another upload-based merger.

How many PDFs can I merge?

You can merge from 2 up to 10 PDFs in one batch, each up to 50 MB. If you need to combine more than 10, merge them in two passes — merge the first 10 into one file, then merge that result with the rest. There is no limit on the number of pages within each file, only on file size and batch count.

Can I reorder pages within a PDF?

You can reorder whole files with Move up and Move down, which sets the order they appear in the merged result. You cannot move individual pages around inside a single PDF with this tool — if you need to delete or rearrange specific pages, use Remove PDF Pages.

Does it work with encrypted PDFs?

Partially. pdf-lib loads files with ignoreEncryption: true, so a PDF that is merely password-protected for opening will usually merge fine. But a PDF that is corrupt, or that uses restrictions pdf-lib cannot parse, will throw a readable error rather than producing a damaged file — so you always know when something didn’t work.