Can I merge large PDFs without uploading them?

Yes. ExactPDF combines PDFs entirely in your browser using WebAssembly and pdf-lib. Open DevTools → Network while merging: you will see zero file uploads. That is the privacy difference versus Smallpdf, iLovePDF, and Adobe online.

What file size can I merge?

Each input PDF can be up to roughly 150 MB on modern hardware — the same headroom advertised on the Merge PDF tool. Total batch size depends on available RAM, but there is no artificial 2-tasks/day cap.

Will quality drop when I merge?

No re-compression happens during a straight merge. Pages are concatenated; vector text and embedded images stay as authored unless you run a separate compress step afterwards.

Does this replace Adobe Acrobat combine?

For merging locally without subscription, yes. Acrobat Pro still wins on preflight print production and redaction legal certs — but for “stitch these PDFs together privately”, browser merge is enough.

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Merge PDF

Privacy

Tutorial

Combine PDFs to 150MB Files — Browser, No Upload

2026-05-02

7 min read

Why merge PDFs locally?

Legal, tax, and HR PDFs often contain PII. The moment you upload them to a “free merge” site, you have lost custody — the file transits TLS to a stranger’s object storage.

ExactPDF merges in your tab using WebAssembly + pdf-lib. Disconnect Wi‑Fi after the page loads: merging still works.