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Sign PDF guide

How to sign a PDF on iPhone or Android

Open the PDF on a phone, draw, type, upload, or pair a signature, place it precisely, and save a signed copy.

Updated September 2026 · PDFKaka EditorialOpen Sign PDF
Capture the Sign PDF workspace at a 390 px mobile viewport with synthetic sample content and the control needed for “How to sign a PDF on iPhone or Android” visible.

Add the visible signature

  1. Choose the PDF and create signature artwork by typing, drawing, uploading, or using the optional phone handoff.
  2. Place and resize the visible mark on the required page or pages.
  3. Reopen the download on the phone and verify every signature mark and required page.

Visible signature artwork versus digital signing

Adds visible artwork, not a certificate-backed digital signature or identity verification. Optional phone pairing transfers only signature PNG data.

FAQ

Is the result a certificate-backed digital signature?

No. PDFKaka adds visible signature artwork. It does not create a certificate-backed cryptographic signature or verify signer identity.

What is the current input limit for Sign PDF?

PDF; optional JPG/PNG signature artwork or phone-captured signature PNG; One PDF ≤50 MiB and ≤500 pages; optional signature image ≤350,000 bytes and ≤2,048 px; ≤200 visible placements.

What does Sign PDF create?

Adds visible signature artwork to PDF pages; this is not cryptographic certificate signing. One PDF ≤150 MiB with visible artwork.

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