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yutils
Example

Input (multiple PDFs)

1. cover.pdf (1 page)
2. main-report.pdf (24 pages)
3. appendix.pdf (8 pages)
(drag to reorder)

Output

merged.pdf (33 pages)
— download instantly via the download button

Note

Built on pdf-lib — fonts, images, and metadata from the originals are preserved. Files stay in browser memory only; nothing is uploaded.

Usage / FAQ

When to use

  • Consolidate multiple scanned PDFs into a single file
  • Combine cover, body, and appendix into one report
  • Bundle project deliverable PDFs at hand-off
  • Produce a single attachment for email (skip multi-attachments)
  • Compile a legal / contract collection

FAQ

Q.Can I merge password-protected PDFs?
A.No — pdf-lib refuses to load encrypted PDFs. Remove the protection first, or work from an unlocked copy.
Q.What about very large PDFs (100MB+)?
A.Technically possible, but browser memory caps (typically 2-4 GB) and processing time will bite. Files over ~50MB can feel slow even in the preview step. Keep individual files small when possible.
Q.Does the merged PDF carry metadata (author, title)?
A.Empty by default. Use a different tool (Acrobat, a metadata editor) for post-processing. Exposing pdf-lib's metadata API is a future decision.
Fun facts

  • PDF was invented by Adobe in 1993 as a proprietary format only Adobe Acrobat could create or read. It wasn't standardized as ISO 32000-1 until 2008 — a full 15 years later. By then PDF was already the de-facto document lingua franca.

    ISO 32000-1

  • PDF supports 'incremental update' — appending changes to the end without modifying the original. That's how digital signatures and edit history work. The side effect: text you 'deleted' may still be in the file (the classic black-bar redaction trap).

    Wikipedia — PDF

  • Fonts are embedded inside PDFs — that's why a 100-page PDF is commonly 10 MB. Font subsetting (embedding only the glyphs actually used) shrinks file size dramatically. It's also why Korean/Chinese PDFs typically weigh more than English ones.

    Wikipedia — PDF Fonts

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