Free Interleave PDFs — Alternate Pages A-B-A-B Online
Interleaving is for when two PDFs belong together page by page — original and translation, question sheet and answer key, before and after scans, or two card decks that must alternate. Drop in PDF A and PDF B and this tool weaves their pages A1, B1, A2, B2… into a single document. If one PDF is longer, its leftover pages are appended at the end. Everything runs in your browser; your files never leave your device.
Interleave PDFs
Weave two PDFs together page by page — A1, B1, A2, B2 — all in your browser.
1 Add PDF A and PDF B
2 Interleave settings
3 Interleave & download
✅ Done — your interleaved PDF
How it works
Add your two PDFs (A and B), choose whether A or B goes first, then hit Interleave PDFs. The tool copies pages one from each source in turn — A1, B1, A2, B2 — using the pdf-lib engine loaded in your browser. If one file has more pages, the extras are appended after the interleaving finishes. Download the woven PDF with one click.
Rule of thumb: interleaving differs from merging — merging stacks B after A; interleaving alternates them. Use interleaving when page pairs belong together (question/answer, source/translation), merging when they don’t.
Everyday uses
- Language study — alternate original and translated pages of a bilingual document.
- Teachers — weave question sheets and answer keys into one alternating handout.
- Scans — combine front-side and back-side scan batches of a double-sided document in the right order.
- Before/after reports — alternate before and after photos of a project so each pair sits together.
- Flashcards — alternate term cards and definition cards into a single printable deck.
Privacy note: interleaving happens with pdf-lib loaded in your own browser — your documents never leave your device.