PDF Merger
Combine multiple PDF files into one with page-level control. Preview thumbnails of every page, deselect pages you don't want, drag to reorder files, and download the merged result. 100% client-side — your files never leave your browser.
Drag your file here, or click to browse
Upload PDF files to merge
How to use
- 1 Drop two or more PDF files onto the upload area, or click to browse — each file appears as a card with page thumbnails for every page.
- 2 Drag file cards up or down to reorder documents — the final PDF follows the sequence you set.
- 3 Click individual page thumbnails to deselect them (dimmed pages are excluded). Use Select All / Deselect All per file to toggle entire documents.
- 4 Review the merged preview strip at the bottom to confirm the final page order before downloading.
- 5 Click "Merge PDFs" — the combined file downloads immediately, containing only your selected pages in your chosen order.
Key features
- Page thumbnails rendered via PDF.js — visually confirm which pages are included before merging
- Drag-to-reorder: rearrange file cards and individual page thumbnails to control the final page sequence
- Per-page selection: click any thumbnail to exclude it from the merged output without removing the file
- Pure client-side merge via pdf-lib — no upload, no server, works with any file size
What is PDF merging?
PDF merging combines multiple PDF documents into a single file, preserving all pages, text, images, fonts, and vector graphics from each source. Unlike printing to PDF or re-scanning documents, a proper merge retains the original quality and keeps the file searchable and selectable — it is a lossless operation that never re-encodes your content.
This tool uses pdf-lib, a pure JavaScript library that runs entirely in your browser. Your files are never uploaded to any server — everything happens locally on your device. You can also select individual pages from each document before merging, deselect pages you don't need, and drag to reorder files — giving you full control over the final document without any third-party software.
Common Use Cases
Combine invoice batches
Merge monthly invoices or receipts into one PDF for accounting or email attachment.
Assemble reports
Join a cover page, table of contents, chapters, and appendices exported from different tools.
Bundle contracts
Combine agreements, annexes, and signature pages into a single document for signing.
Collect scanned pages
Merge scans done one page at a time into a complete multi-page document.
Developer documentation
Join API docs, changelogs, and setup guides into a portable single PDF.
Selective page extraction
Deselect pages you don't need before merging — effectively extracting only what matters.
How PDF merging works
Each PDF is a self-contained document with its own object table, fonts, images, and page tree. Merging re-indexes these objects into a new shared document without re-encoding content.
| Step | What happens |
|---|---|
| 1. Parse | Each uploaded PDF is parsed in memory — the page tree, fonts, and embedded objects are identified. |
| 2. Copy pages | Selected pages (and their referenced resources) are deep-copied into a new empty PDF document. |
| 3. Re-index | Object IDs are remapped to avoid conflicts between source files. Fonts and images used by multiple pages are deduplicated when possible. |
| 4. Serialize | The merged document is serialized to binary and offered as a download — no lossy re-encoding occurs. |
Tips & limitations
100% private — no upload
Processing happens entirely in your browser with WebAssembly and JavaScript. Files never leave your device.
Page selection
Click any page thumbnail to toggle it. Deselected pages (dimmed) are excluded from the final PDF.
Password-protected PDFs
Encrypted PDFs may fail to load. Unlock them first with your PDF reader before merging.
Large files
Very large PDFs (100+ MB) may be slow to render thumbnails depending on your device's CPU. The merge itself is fast regardless. There is no hard file size limit — only your browser's available memory.
Preserves interactivity
Merged PDFs retain hyperlinks, bookmarks, annotations, and form fields from the source files when pdf-lib supports passing them through.
Frequently Asked Questions
Can I merge password-protected PDFs?
Encrypted PDFs may fail to load in the browser. You need to unlock them first using your PDF reader (Adobe Acrobat, Preview, or any PDF software) before uploading them to this tool. The tool works with any unlocked PDF regardless of its original security settings.
Does PDF merging reduce quality?
No. This tool performs a lossless merge — it copies pages from the source documents into a new PDF without re-encoding text, images, fonts, or vector graphics. The output has the exact same quality as the originals. This is unlike "printing to PDF" which often downscales images or flattens transparency.
Is there a limit on the number of files I can merge?
There is no hard limit imposed by the tool. The only constraints are your browser's available memory and the total page count of all uploaded files. For typical documents (under 100 pages each), merging 5-10 files works without issues. Very large batches may take longer to render thumbnails.
Are hyperlinks and bookmarks preserved after merging?
When using pdf-lib, hyperlinks, bookmarks, annotations, and form fields from the source PDFs are preserved in the merged output whenever possible. Some complex interactive elements created by specialized PDF editors may not carry through — test a sample first for critical documents.
Do I need to create an account to use this tool?
No. This tool is completely free and requires no account, sign-up, or payment. It runs 100% in your browser — your files never leave your device — so there is no server-side processing, no file storage, and no data collection of any kind.