Merge PDF Files into One Document
Add two or more PDFs, put them in the right order and join them into a single file. Every page is copied exactly as it is — nothing is re-compressed or re-rendered.
How to merge PDF files
- Choose two or more PDF files, or drag them onto the drop area. You can add more files at any time.
- Check the list: each file shows its size and page count. Use the up and down arrows (or drag a row) to set the order.
- Select Merge. The pages are copied in a background worker; you can cancel at any point.
- Download the merged PDF.
Supported formats
- Input
- Output
- Maximum size
- 200 MB per file (limited by your device's memory)
What is kept when PDFs are merged
Page content, fonts, images, page sizes and rotation are copied unchanged, so the merged file looks identical to the originals. Document-level extras such as bookmarks (outlines), the original title and interactive form fields are not carried over, because each source file defines them independently. If you only need part of a document in the result, take those pages out first with the PDF Page Extractor, and if the merged file is too large to email, run it through the PDF Compressor.
Benefits
- Lossless: pages are copied as PDF objects, not converted to images, so text stays selectable.
- Keyboard-accessible ordering with move up/down buttons, plus drag and drop for mouse users.
- Files never leave your device — useful for contracts, payslips and medical records.
Limitations
- Encrypted PDFs (with an open password or permission restrictions) can't be merged; remove the protection in a PDF reader first.
- Bookmarks, form fields and document-level attachments of the source files are not preserved.
- Very large combined jobs (several hundred MB) can exhaust browser memory, especially on phones.
Privacy and security
The PDFs are read with the File API and merged by pdf-lib inside a Web Worker running in this tab. No file, file name or page content is uploaded; the merged PDF is created in memory and handed to your browser as a download.
Read our privacy policy for details about the site as a whole.
Frequently asked questions
Does merging reduce the quality of my PDFs?
No. The pages are copied as they are — text, vector graphics and embedded images are not re-encoded. The merged file is usually close to the sum of the input sizes.
Why is one of my files marked as encrypted?
That PDF has a security handler (an open password or restrictions on copying/editing). Its contents are encrypted, so pages can't be copied into a new file. Open it in a reader that knows the password, save or print it to an unprotected PDF, then add it again.
How many files can I merge at once?
Up to 50 files of 200 MB each. In practice the limit is your device's memory: the inputs and the result are all held in RAM while merging.