PDF Merger

Merge PDF files in your browser, in the order you choose

Drop two or more PDFs into the box above, drag them into the order you want with the up and down arrows, and press Merge PDFs. You get one combined file back, downloaded straight from the page. The tool reads each file's page count as you add it, so you can confirm you picked up the right documents before you commit to an order.

The whole merge runs inside the browser tab. Your files are read with the browser's own file API, combined by a JavaScript PDF library loaded with the page, and handed back to you as a local download. Nothing is sent to a server, because there is no upload step in the code at all — no request is made with your file, so there is nothing on our side to store, log, or delete. If you disconnect from the network after the page finishes loading, the merge still works. That matters if the documents are signed contracts, medical records, tax returns, or anything else covered by a policy that says "do not upload client data to third–party websites."

Getting the page order right

Order is the part people get wrong, and it is the part that is annoying to undo. Two rules make it predictable:

• Files merge top to bottom, in list order. The first file in the list supplies page 1. There is no sorting by filename, date, or size — the list is exactly the order you dropped or selected the files in, and the arrows are the only thing that changes it.
• Pages inside a file keep their internal order. The merge never interleaves. If you need pages from two documents alternating — say, a scanned signature page slotted into the middle of a digital agreement — split the agreement at the insertion point first, then merge three pieces in sequence.

Because reordering after the fact means merging again from scratch, it is worth checking the list before you press the button. The header line shows the file count and the running total of pages, which is the fastest sanity check available: if you expected a 47–page deal package and the counter says 44, one exhibit is missing and you can see it before you produce the file, not after you email it.

A worked example: assembling a signed contract package

You have msa-draft.pdf (12 pages, produced from Word), signature-page-scanned.pdf (1 page, photographed and scanned at the closing), and exhibit-a-pricing.pdf (3 pages, exported from a spreadsheet). Drop all three in. The list shows three rows, 16 total pages. Drag the scanned signature page to position 2 with the up arrow, leave the exhibit last, merge. You get a 16–page file where pages 1–12 are crisp vector text, page 13 is a scan, and pages 14–16 are the pricing table. The result is one file with three very different kinds of page in it, which is normal and fine — and it leads directly to the next thing people ask about.

Mixed page sizes and orientations

PDF stores a page size per page, not per document. Each page carries its own MediaBox — the rectangle that defines its dimensions — and its own rotation value. A merge copies pages as they are, so those attributes travel with them.

The practical consequence: this tool does not resize, rescale, or reorient anything. If you merge a US Letter report with an A4 report, the output has Letter pages and A4 pages in the same file. Nothing is cropped and nothing is stretched; the pages are simply different sizes, which most PDF viewers handle by fitting each page to the window as you scroll. A landscape spreadsheet export merged into a portrait document stays landscape.

Rotation deserves the extra warning. A page scanned sideways looks sideways after merging, and correcting it means going back to the source file — there is no rotate control here. Fix orientation before you assemble, not after.

What survives the merge, and what does not

This is the honest part, and it is where a browser–side merge differs from a full desktop PDF editor. Page content is copied faithfully: text, vectors, embedded images, and embedded fonts all come across intact. Document–level structures are a different story, because they live outside the pages and each source file has its own version of them.

Bookmarks

A PDF outline is a tree of destinations stored once for the whole document. When pages are copied into a fresh document, the outline is not rebuilt, so the merged file has no bookmarks even if every source file had them. For a package that a reader will scroll through, this is a non–issue. For a 300–page reference manual where navigation is the point, it is a real loss, and you want a desktop editor that rewrites the outline.

Form fields

If your PDFs contain fillable fields, the merge is the wrong tool. Fields are entries in a document–level form dictionary; the page only holds the visual widget. Copying pages leaves the widget behind without its field definition, so what was an editable box becomes at best inert. There is a second problem even in tools that do handle forms: two files that both contain a field called Name collide, and one silently overwrites the other. If you need the merged file to stay fillable, do not merge it here. If you only need the answers preserved, flatten each form first — print to PDF, or use your viewer's flatten command — which converts the filled values into ordinary page content that copies perfectly.

Annotations and comments

Highlights, sticky notes, and stamps are page–level annotations and generally travel with their page. Treat them as best–effort rather than guaranteed: if a review comment thread is legally or procedurally important, verify it in the output before you rely on it, or flatten the markup into the page first.

Merging scanned pages with digital ones

A "digital" or text–native PDF holds real text objects and font programs. A scanned PDF holds a photograph of a page — one large image per sheet — and, if the scanner ran OCR, an invisible text layer positioned over it. Merging the two kinds is completely legitimate and extremely common, but expect these effects in the combined file:

• Size is dominated by the scans. A twelve–page text document might be a few hundred kilobytes; a single colour scan at high resolution can exceed that on its own. The merged total is roughly the sum of the inputs, so a package that is mostly scans will be large.
• Search stops at the scans unless those pages carry an OCR layer. If you can select text in the scanned file before merging, you can search it after; if you cannot, merging will not create that ability. Nothing here performs OCR.
• Visual quality is inconsistent — sharp type on one page, a grey–cast photograph of type on the next. That is a property of the source, not of the merge.
• Scan dimensions are often slightly off standard, because scanners record the actual scanned area. A page that measures 8.5 × 11.02 inches next to exact Letter pages is normal.

If the merged package is too large to send, the fix is compression of the scanned pages specifically, which is a separate job from combining files.

Limits, errors, and edge cases

• Two files minimum. The merge button stays disabled with one file, since there is nothing to combine.
• PDFs only. Anything the browser does not report as application/pdf is rejected by name with a message. Images, Word documents, and ZIP archives are not converted — export them to PDF first.
• Encrypted and password–protected files fail to load, and you will see a message saying the file may be corrupted or encrypted. Remove the password in a viewer that can open it, save an unprotected copy, then merge. This includes files with an owner password that permits opening but restricts editing.
• Damaged files produce the same message. A PDF that opens in one viewer and not another is often truncated — re–download or re–export it.
• Memory is the real size ceiling. Every file is held in the tab's memory, and so is the output. Very large scanned batches can exhaust a tab, especially on a phone or a machine with a lot of other tabs open. Merge in stages if you hit it: combine in groups, then merge the groups.
• The output is always named merged.pdf. Rename it after downloading.
• Changing the list clears the result. Removing a file or moving one after a merge discards the download link so you cannot accidentally keep a stale file. Merge again.

Does merging reduce quality?

No. Page content streams are copied, not re–rendered and not re–encoded. An image that was 300 DPI in the source is the same image in the output, and text stays text. What you lose is document–level structure, as listed above — not fidelity.

How large will the merged file be?

Roughly the sum of the inputs. It can come out slightly smaller when the sources carried unused objects, and slightly larger when several files embed subsets of the same font, since each subset is copied separately and they are not deduplicated. Do not expect a merge to save space.

Can I merge the same file twice?

Yes. Add it twice and it appears as two rows, each with its own remove button, and its pages appear twice in the output — occasionally useful for duplicating a cover sheet or a terms page.

When to use something else

Reach for a desktop PDF editor when you need the merged document to keep a working bookmark tree, when the file must remain a fillable form, when pages must be normalised to a single paper size for printing, or when you need to delete or rotate individual pages as part of the same operation. This tool does one job — concatenating whole documents in an order you control, privately, with nothing leaving your machine — and for assembling an exhibit set, a closing binder, an expense claim, or a scanned application package, that is the whole job.