PDF Merger

PDF Merger combines any number of PDF documents into a single output file. Everything happens in your browser using pdf-lib, an open-source JavaScript library that reads and writes the PDF format directly. There is no upload step, no temporary copy on our infrastructure, and no account requirement — when you select files, they're loaded into a Blob in your tab's memory and processed there.

After dropping files in, you can drag rows up and down to set the order they'll appear in the output. The merged PDF follows that order exactly. Each row also has a Pages button that expands a thumbnail strip; from there you can rotate individual pages 90° at a time before merging. Rotations are stored per-page in the document's metadata and applied to the output, so a sideways scanned page becomes upright in the final file without re-rendering.

Because pdf-lib copies the page objects byte-for-byte from the source files into the new document, nothing about the original pages changes during merging. Fonts stay embedded, vector graphics stay vector, hyperlinks remain clickable, and image quality is unchanged. This is the same approach used by Adobe Acrobat's combine-files feature — there's no re-rendering or re-compression involved.

The browser's memory is the only practical limit on how many files you can merge. On a modern laptop you can comfortably combine 50+ PDFs totalling several hundred megabytes. Very large jobs (1 GB+ of input) may slow the browser tab; in those cases, merge in two passes or use a desktop tool like pdftk.

PDF Merger does not flatten form fields, rasterize annotations, or run OCR. If you need any of those steps, run them on each input file first using the relevant tool below, then merge. Likewise, encrypted (password-protected) PDFs must be unlocked before they can be merged — pdf-lib refuses to parse encrypted streams.

After merging, you can pipe the output into the next tool in this set: compress to shrink the file size for email, add a password if it contains anything sensitive, or stamp a watermark across every page. The Workflow Next strip below links straight to those next steps.

If your real need is to rearrange or remove pages inside one existing file (rather than combining multiple files), use the PDF Page Organizer instead — it's purpose-built for that and gives you a single drag-and-drop view of every page in one document.