Merge PDF
Combine multiple PDF files into one — all processing happens in your browser.
Deep Dive
Combine multiple PDF files into a single document in any order using pdf-lib running in your browser. Drag and drop files to reorder them before merging. No files are sent to a server — merging is entirely local.
Who uses this?
- Combining multiple invoice PDFs into a single monthly report
- Assembling chapters of a document written in separate files
- Merging a cover page with a main document
- Combining form pages before submission
Common Errors & Fixes
Some pages are blank in the merged PDF
The source PDF may have blank pages intentionally, or it uses features (like embedded forms) that pdf-lib renders as blank. Inspect the source files.
Merge fails with a large number of files
Split the task into two batches. Merge the first half, then merge that result with the second half.
Expert FAQ
Is there a limit on the number of files I can merge?
There is no hard limit, but very large or numerous PDFs may exhaust browser memory. Merging up to 20 typical documents is generally reliable.
Are bookmarks and links preserved?
Internal links may break after merging since page numbers shift. External links and basic content are preserved.
Can I merge password-protected PDFs?
No. Encrypted PDFs must be unlocked first. Use a PDF reader to remove the password, then merge.