How to merge PDF files in order and check the result

Start with the order of the documents

For a project submission, a useful example is cover → main report → supporting figures → appendices. An organization may require a different order, so follow its instructions first.

Numbering your source filenames can help prevent mix-ups. Inside the merger, you can arrange the selected files with the Up/Down controls or by dragging items into the preferred order.

• Confirm which document should appear first
• Remove duplicate or outdated attachments
• Check landscape pages and rotated scans before merging

Merge the files without uploading them

Open the PDF merger, select your source documents, check the order shown on screen and run the merge. Download the resulting file and keep the originals until the output has been checked.

The current tool supports 1–8 selected PDFs, up to 60MiB combined and 250 total pages. Larger or complicated documents may require splitting the task into smaller groups. Performance also depends on your device and the PDF structure.

• Choose files → arrange order → merge → download
• Test a smaller set if a large file fails to process
• Keep the originals as your reference copies

Worked example: three files and nine pages

Suppose Cover.pdf has 1 page, Report.pdf has 5 pages and Appendix.pdf has 3 pages. Merging those files in that order produces a 9-page PDF: cover on page 1, report on pages 2–6 and appendix on pages 7–9.

A wrong file order produces the same total number of pages. Check the transitions between documents, such as pages 1–2 and 6–7, rather than relying only on the page count.

What can change during a PDF merge?

Copying pages is not the same as preserving every document-level feature. Depending on the source files and library behavior, interactive forms, bookmarks, attachments or digital-signature validation may not survive as expected. The pdf-lib documentation explicitly notes that copied documents may omit features such as AcroForms and outlines.

If your submission depends on a cryptographic signature or an editable PDF form, confirm the receiving organization’s requirements before merging. A saved copy should not be assumed to retain the original signature validity.

• Page count, order and orientation
• Text, tables, images and embedded fonts
• Form fields, bookmarks, attachments and digital signatures
• Required file name and upload size limits

Handling private documents

The current PangPang Tools merge operation reads selected PDFs in your browser and generates a downloadable result without uploading those PDFs to the site server. This avoids the need to send your document content to a web service for the merge itself.

Local processing does not automatically remove downloaded files or copies on a shared computer. Review the download destination and keep or delete document copies according to your own retention requirements.