Merge PDF

Purpose

Combine multiple PDF files into a single PDF, with full control over page order and the ability to insert blank pages anywhere. Everything runs locally in your browser — your files are never uploaded to any server. Free, no file count limit, no watermark, no sign-up. Merged output preserves original fonts, image quality and selectable text layers — no quality loss from re-encoding. Ideal for combining scanned receipts, contract attachments and report chapters into one document for submission or archival.

Steps

1. Drag multiple PDFs into the page, or click "Select files" to add them in batch
2. Review the thumbnail grid — each file is color-coded
3. Drag cards to reorder pages, mixing across source files freely
4. (Optional) Click "+ Add blank page" to insert a blank page between any two pages
5. Pick blank page size (A4, Letter, or match the previous page)
6. Click the × on any thumbnail to drop a page
7. Click "Process" once the order looks right
8. The merged PDF downloads automatically as merged.pdf
9. Click "Reset" if you want to start a different merge

FAQ

Will my PDFs be uploaded to a server?

No. All merging happens in your browser via the pdf-lib library — your files never leave your device. You can even use the tool offline once the page has loaded. Check your DevTools Network panel: zero file upload requests during processing.

Is there a limit on file count or total size?

No hard limit. Tens or even a hundred files work in practice; the actual ceiling depends on your device's available memory. Ten files under 10MB each is silky-smooth; total inputs above 200MB may slow older browsers, in which case split into batches.

Will fonts get garbled or lost after merging?

No. Merging doesn't re-render text or fonts — embedded fonts, vector art and selectable text layers are preserved as-is. If a source file has a font issue, the merged output shows the same issue (it's the source's problem, not the merger's).

How do I change page order?

After upload, pages appear as a thumbnail grid. Drag any thumbnail to a new position. You can also interleave pages across multiple source files — for example, sandwich page 3 of A.pdf between pages 2 and 3 of B.pdf.

Will the merged PDF be larger than the sum of sources?

Usually slightly smaller, because duplicate font subsets and resources get deduplicated. If the result is noticeably larger, it's typically because source files used different font subsets — a PDF structural quirk, not a merger bug. For further size reduction, run the merged file through the Compress tool.

Use cases

• Combine scanned receipts, contract attachments and statements into one expense submission for finance
• Stitch report chapters, table of contents and appendices into a complete thesis or proposal
• Merge meeting photo PDFs with minutes for archival
• Combine multi-volume ebooks into a single readable file
• Bundle multiple student assignment PDFs for batch printing

Tip

If sources include scans, run OCR first to give each file a searchable text layer — the merged result will then be fully searchable. For very large merges, compress each source individually first to reduce the final size.