🧩 Merge PDF

How the ordering list works, end to end

Drop several PDFs onto the upload zone, or select them all at once with the Ctrl / Shift multi-select in the file picker. Each accepted file — anything with a .pdf extension or the application/pdf MIME type — appears as its own row showing number, filename and size. Files you add later simply append to the bottom of the list, so uploading in two batches is fine.

The row controls are deliberately minimal. The up arrow moves a file one position earlier, the down arrow one later, and they disable themselves at the ends of the list so you cannot push a cover past the start. The X removes the row entirely. The moment you hit Merge, pdf-lib opens every file, copies every page in list order into a fresh document, and saves one combined PDF back to you — pages come out in exactly the sequence the list shows.

• Reordering is free before you merge: shuffle rows as many times as you like, nothing is written out until the button is pressed.
• If a file turns out to be the wrong one, X it out; if you accidentally skipped a file, just drop it again — it appends at the end and you can move it.
• The downloaded file is named merged.pdf; rename it in the save dialog if you need a more specific title.

The everyday jobs this tool exists for

The classic use case is an application packet: a cover sheet, a signed form, a certificate and a transcript all arrive as separate PDFs from different departments, and a recruiter refuses four attachments but accepts one. This tool collapses that stack into a single document whose page order you control. The same flow applies to invoices from multiple suppliers, lecture slides split across two exports, and a book chapter assembled from individual scans.

Merging is also the complement to the rest of the PDF toolbox. After you split a big deck into the sections you actually need, you can re-add them in a different order and merge them back. Once the combined file is downloaded, run it through the PDF compressor before emailing it if the attachment meter is close to its limit, and stamp the whole packet with page numbers so references like "see page 4" are unambiguous. For documents you need to quote or archive as pictures, the PDF to image converter handles the raster side.

What survives a merge — and what does not

Knowing what the merged document will look like saves surprises. Every page keeps its own dimensions, orientation and rotation: portrait pages stay portrait, landscape slides stay landscape, and a rotated scan stays rotated. Embedded fonts and vector graphics on each page are copied as-is, so typography inside each source PDF does not change. Mixed paper sizes are fine — Letter and A4 pages can share a file and print at their own sizes.

A few things do not travel across. Because the engine builds a fresh document, per-file bookmarks (outline trees), interactive form fields, embedded file attachments and document-level metadata (author, title, subject) are not carried over; the output reads as one clean flat document. Password-protected source files cannot be opened by the local engine and are rejected up front, so unlock each file first. If your workflow depends on clickable outlines or fill-in forms, keep the originals for editing and treat the merged PDF as the reading or sending copy.

Frequently Asked Questions