Flatten PDF Forms and Annotations Online
Merge all form fields, annotations, and layers into a single document object to prevent further editing.
How to flatten a PDF — 3 steps
- 1
Add your PDF
Drop the filled form or annotated document into the box above.
- 2
Flatten the layers
Form fields, annotations, and markup are merged into the page content itself, becoming ordinary, uneditable page graphics.
- 3
Download the locked copy
Save the flattened PDF. What you see is now permanently what everyone gets — in every viewer.
Why flattening matters before you share a form
A filled PDF form is not as final as it looks: the answers live in editable form fields, and anyone with a PDF viewer can click into a field and change the value — no special software required. The same goes for annotations and markup, which most viewers let recipients move or delete. Flattening converts all of it into fixed page content, like ink on paper.
That makes flattening the right last step for applications, signed agreements, invoices, graded work, and any form whose values must not change after submission. It also fixes a common compatibility headache: filled forms that display blank or wrong in certain viewers and print drivers, because the field data is rendered inconsistently. Flattened pages render identically everywhere.
Flatten after everything else is done — the operation is one-way by design, so keep your editable original on your device (it never leaves anyway) in case you need to make changes later and re-flatten a fresh copy.
Your files never leave your device
Forms usually contain exactly the data you don't want on someone else's server — names, addresses, signatures — so flattening here happens only on your device.
Most online PDF sites upload your document to their servers, process it there, and keep a copy for minutes, hours, or longer. PilotPDF works differently: the page downloads a small processing engine into your browser, and your file is opened and edited in your device's memory using WebAssembly. Nothing is transmitted, so there is nothing for a server to store, leak, or scan. You can even disconnect from the internet after the page loads and the tool keeps working.
Read more about how this works in our privacy-by-design explainer.