How to Merge PDF Files Online — Combine PDFs for Free
Merging PDFs combines two or more separate documents into a single file that flows page-by-page, is easier to share, and counts as one attachment. Rather than sending a six-file application package and hoping the recipient opens everything, a merged PDF keeps all content in sequence — cover letter, CV, portfolio, certificates — as one coherent document.
How the merge works in your browser
This tool uses the PDF-lib JavaScript library to load each PDF, copy its pages into a new document in order, and write the combined result to a downloadable Blob. The operation runs entirely inside your browser — your files are never sent to a server. The merged PDF inherits the page sizes of its source documents; if you are merging landscape and portrait pages, each page keeps its original orientation.
Controlling the merge order
After uploading, each PDF appears as a row in the file list. Drag the handle on the left to rearrange files before merging. This lets you put a cover page first, appendices last, and correctly sequence multi-part reports. The final merged PDF will follow exactly the order you set.
Common use cases for combining PDFs
Job applications: merge CV, cover letter, certificates, and portfolio into one attachment. Legal filings: combine a contract body with its exhibits and addenda. University submissions: package a thesis draft, signed declaration, and ethics approval into a single upload. Financial reporting: merge quarterly statements into an annual pack. Insurance claims: combine the claim form, photos, and receipts for the adjuster.
Size and password considerations
The tool merges all readable pages from each PDF. If a source file is password-protected, you will need to remove the password first before adding it to the merge queue. After merging, if the combined file is large, run it through the PDF compressor to reduce its size before uploading or emailing. To add a watermark or page numbers to the merged result, use the PDF watermark tool or page numbering tool.
Related PDF tools
Need the reverse operation? Split a PDF to separate it into individual files. To extract specific pages as images, use PDF to JPG. To combine images rather than PDFs, start with the JPG to PDF converter.