Contracts with the signature page in a second file, a report whose appendix lives elsewhere, scanned pages in the wrong order — merging is the PDF job everyone meets. Add your files, arrange them, and this page stitches them into a single PDF, on your device, with page content copied losslessly from the originals.
How it works
The page reads each PDF with pdf-lib (an open-source library that runs locally in your browser), copies every page — in the order shown in your list — into a fresh document, and offers it as a download. Because pages are copied at the document level rather than re-rendered, text stays selectable, links and vector graphics survive, and quality is identical to the originals. Encrypted files that open without a password are handled too; a file protected by an open password needs unlocking first.
Order matters
Files merge strictly in list order, top to bottom. Use the ↑ and ↓ buttons to fix the sequence before merging — the merged file's page numbers simply run through your list from first to last. If you need pages interleaved (fronts and backs from a single-sided scanner, for example), merge first and then use the Split tool's page ranges to rebuild the order.
Private by design
Like every CalcViso file tool, this one runs entirely in your browser. The file you choose is read by this page, processed on your device, and offered back as a download — it is never uploaded to a server, never stored, and never seen by anyone else. Close the tab and it is gone from memory.
Worked example
Try the sample button: it creates two small PDFs (3 pages and 2 pages) right in your browser. Merge them and the result is a single 5-page PDF — open it and check that pages run A1, A2, A3, B1, B2 in order.
How to use this tool
- Drop two or more PDFs onto the box, or click to choose them.
- Check each file's page count in the list, and reorder with ↑ / ↓.
- Remove any file you added by mistake with ✕.
- Press Merge PDFs and download the combined file.
Merging big files
Everything happens in your device's memory, so very large files (hundreds of megabytes) can strain a phone or an old laptop. On a desktop there is effectively no page limit. If a merge fails on a phone, try two files at a time, or merge in stages — merge A+B, then merge the result with C.