Flatten PDF Online — Lock Form Fields & Annotations

Merge interactive form fields, signatures, and markup into the page layer so recipients cannot edit fields after submission.

Why flatten interactive PDFs

Fillable PDF forms keep field values in a separate layer — recipients can still tab between boxes or change answers. Flattening merges those values into the page so the document behaves like a flat scan.

Common workflows

IRS/tax forms after data entry
HR onboarding packets with typed signatures
Insurance claims before portal upload
Design proofs with approval stamps

Pair with Password Protect PDF after flattening if the final pack must stay read-only.

Security & retention

Files are uploaded over HTTPS, processed on our servers, and stored only long enough for you to download the result. Temporary copies are removed automatically; we do not use your documents to train models or build marketing lists.

Free vs Pro

Free — 3 conversions per tool per day, 200 MB per file.
Pro — unlimited use, 4 GB uploads, priority conversion queue. See plans.