PDF Merger
Combine multiple PDF documents into a single file.
PDF Merger combines two or more PDF files into a single document entirely in your browser. You choose the files, set the order with drag-and-drop or the move buttons, and download one finished PDF — no account, no upload to a server for processing, and no watermark on the result.
Use it when you need to stitch contracts, scans, receipts, or chapter drafts together without installing desktop software. Because merging runs locally with pdf-lib, your documents stay on the device unless your browser itself sends them somewhere else (it does not for this tool).
How it works
When you add PDFs, the tool keeps each file in page memory as a list item with an id, name, and File object. Dragging a row or using the up/down chevrons rewrites that list order; adding or removing a file clears any previous merge result so you cannot download a stale file by mistake.
Merging creates a new empty PDF document, walks your ordered list, loads each file’s bytes, copies every page from the source, and appends those pages to the new document. The finished bytes become a Blob URL for download — the original files are never rewritten on disk.
How to use
- Open PDF Merger and drop or click to add PDF files in the upload zone (accept type is application/pdf).
- Confirm non-PDF drops — the tool warns and ignores files that are not PDFs.
- Review the Selected Files list: each row shows an index, file name, grip handle, and remove control.
- Drag by the grip handle, or use the chevron buttons, so files appear in the order you want in the output.
- Remove any file you no longer need, or Clear All to start over (this also discards a previous merge result).
- Select Merge PDFs — the button enables only when at least two files are in the list.
- Wait for the Merger Complete alert; the step indicator moves to Download.
- Optionally edit the output file name (default Merged_Document), then download the merged PDF.
Tips
- Merge at least two files — the action is disabled with one file so you cannot produce a no-op download.
- Changing the list after a merge always resets the result; merge again if you reorder or remove anything.
- Very large or corrupted PDFs can fail on load; password-protected sources are rejected by the parser.
- Name the output before download so the file matches your filing scheme instead of Merged_Document.pdf.
PDF Merger FAQ
Are my PDF files uploaded to a server?
No. Merging runs in the browser with pdf-lib. Files are read from your device into page memory and are not sent to InBrowserKit for processing.
How many PDFs can I merge?
There is no fixed count in the tool; the practical limit is browser memory. Very large batches on phones may fail — try a desktop browser for heavy jobs.
Can I control the page order inside the output?
The output follows the file list order top to bottom. All pages from each file are copied in their original page order; to extract or reorder individual pages, use a split or organize PDF tool first.
Why is Merge PDFs disabled?
The button stays disabled until at least two valid PDFs are selected. Add another file in the drop zone to enable it.
Does merging change the original PDF files?
No. Originals are only read. The tool writes a new document into a temporary blob URL for download; clearing or reloading the page discards that result.
What if a PDF is password protected or damaged?
Load can fail for encrypted or corrupted files. The tool shows an error toast suggesting corruption or password protection — unlock or re-export the file, then add it again.
Credits
- pdf-lib — Create, modify, and serialize PDF documents in the browser