Merge multiple PDF files into one — drag to reorder pages before combining. Supports unlimited files, runs 100% in your browser with no file size limits imposed by servers.
Drop your PDF here or click to browse
Files are processed entirely in your browser — nothing is uploaded to any server
Click the upload area or drag and drop your file. Upload two or more PDF files — drag the file cards to reorder them as needed, then click Merge to combine them into a single PDF and download.
Adjust the tool options to match your requirements — all settings are explained with helpful labels and previews where applicable.
Click the action button to process your file instantly in your browser. Download the output — no waiting, no email, no account required.
There is no hard limit on the number of files you can merge — the only constraint is your browser's available memory. In practice, merging 20–50 PDFs of typical size works smoothly on any modern device. For very large batches (100+ files or total size exceeding 1GB), we recommend merging in groups of 20–30 files and then merging the resulting files together in a second pass.
Yes — after uploading, each file appears as a card in the file list. Drag and drop the cards to reorder the files before merging. The merged PDF will follow the exact order shown in the list. This is useful when combining documents where the order matters — for example, placing a cover letter before a CV, or ordering monthly reports chronologically.
Internal hyperlinks and document bookmarks (PDF outlines) within each individual file are preserved in the merged output where possible. Cross-document links (a link in document A pointing to a page in document B) will need manual updating after merging. Annotations, form fields and digital signatures may be affected by the merge process depending on the original file structure.
Yes — you can merge PDFs with mixed page sizes (e.g. A4 portrait, A3 landscape, US Letter) into a single document. Each page retains its original dimensions. The merged PDF will contain mixed page sizes, which is valid PDF format and supported by all major readers. If you need all pages to be the same size, consider using a PDF resize tool before merging.
Password-protected PDFs with an open password cannot be merged without first unlocking them. Use our Unlock PDF tool to remove the password, then include the unlocked file in your merge. PDFs with only permissions restrictions (printing/copying disabled but no open password) can usually be merged since the document itself is accessible — the output merged file will not carry forward the original restrictions.
PDF form fields are preserved in the merged output. However, if two source PDFs contain form fields with the same internal name, they may conflict in the merged document. To avoid this, it is best practice to flatten forms (convert form field values to static text) before merging. Most PDF editors offer a "flatten fields" option. Alternatively, fill in and save forms before merging.
The merged PDF will be approximately the same size as the combined total of all input files. In some cases it may be slightly smaller if duplicate embedded resources (fonts, colour profiles) are deduplicated during the merge. The tool does not re-compress or re-render any content, so there is no quality loss and no significant size increase from the merge process itself.
Yes — scanned PDFs (image-based PDFs where each page is a photograph of a document) can be merged exactly like text-based PDFs. The scanned page images are transferred directly into the merged PDF without any re-processing. Note that scanned PDFs are typically larger in file size than text-based PDFs. If the merged file is very large, PDF compression tools can reduce the file size after merging.
Yes — digital signatures embedded in a PDF are mathematically tied to the exact byte content of the file. Any modification to the file — including merging — invalidates existing digital signatures. If the source documents contain valid digital signatures that need to be preserved, do not merge them. The merged output will show the signatures as invalid. For compliance purposes, archived signed originals separately alongside merged working copies.
No — all PDF merging is performed entirely within your browser using the PDF-lib JavaScript library. Your files are never uploaded to any server. This makes the tool safe for confidential documents such as legal contracts, medical records, financial reports and HR documents. No data is logged, retained or shared. You can even use this tool offline by loading the page before disconnecting from the internet.
