Merge PDF Files Online

Merge PDF combines two or more PDF files into a single document in the order you choose. It is the quickest way to turn separate invoices, scanned pages, report chapters or signed forms into one tidy file you can send, print or archive. Everything happens in your browser: your PDFs are never uploaded, so even confidential contracts stay on your device.

How to merge PDF files

1. Add your PDFs. Drop at least two files onto the upload area or click to pick them. You can add more files at any time with the add button.
2. Set the order. Files are merged from top to bottom. Use the up and down arrows next to each file to move it, and remove any file you added by mistake.
3. Choose advanced options (optional). Keep the original page sizes, or fit every page to A4 or Letter. Turn on “Start each file on a new sheet” if you plan to print double-sided.
4. Click Merge PDF. The combined file is built in a few seconds and a summary shows how many files and pages went into it. Download the result, named after your first file with “-merged”.

Options that make a difference

• Keep original page size (default): every page is copied exactly as it is, so text stays selectable, images keep their full resolution and nothing is re-compressed.
• A4 or Letter: useful when you combine documents of mixed sizes, such as a Letter-size contract with A4 annexes or small receipts with full pages. Each page is scaled to fit the chosen paper, centred, and keeps its portrait or landscape orientation.
• Start each file on a new sheet: when a file ends on an odd page, a blank page is inserted so the next file begins on the front of a new sheet. That way two-sided printouts can be separated cleanly.

Practical uses

• Application packs: put a cover letter, CV, certificates and references into one PDF, which many job portals and visa forms require.
• Accounting: collect a month of invoices or receipts into a single file for your accountant or expense report.
• Scanned documents: scanners often save each page or each batch as a separate file. Merge them, then fix the page order with Organize PDF.
• Reports and theses: join chapters exported from different programs, then add consistent page numbers across the whole document.

Tips for a clean result

• Name your files with a number prefix (01, 02, 03) before adding them. They will be easier to put in the right order.
• Password-protected PDFs cannot be merged. Unlock them first with Remove PDF Password if you know the password.
• If your pages are photos rather than PDFs, convert them first with JPG to PDF, then merge.
• A merged file is roughly the sum of its parts. If it is too large to email, run it through Compress PDF afterwards.

Why merge PDFs with WoowPDF

The merge runs locally with a PDF engine loaded in your browser, so there is no upload wait and no copy of your files on anyone’s server. You can add files of up to 100 MB each, and the number of files is limited only by your device’s memory. The tool is free, requires no account, adds no watermark and has no daily limit. It works in any modern browser on Windows, macOS, Linux, Android and iOS.