Free · No sign-up · Runs in your browser

Flatten a PDF.

Lock filled-in form answers, comments, stamps and signatures into the page so they can’t be changed, look the same in every app and don’t vanish when printed. Ideal before you email a completed form.

Not uploaded — nobody sees it Form text stays sharp Comments and stamps too No sign-up, no watermark

Drop your PDF here, or click to browse Filled-in forms, signed or commented PDFs · one at a time

What to flatten

Your file is never uploaded — it’s processed right here in this browser tab, on your device. It never reaches a server, so we never see it, copy it or keep it.

At a glance

Flatten PDF: quick facts

Lock form answers, comments and signatures into the page.

Updated 8 October 2026

Price: Free. No sign-up, no watermark.
Options: Form fields (text stays sharp and searchable) or Everything (pages redrawn at 200 dpi).
Good for: Filled-in forms, applications and contracts before sending.
Note: Flattening breaks certificate-based digital signatures, so flatten first, then sign.
Privacy: Your file is processed in your browser and never uploaded.

How it works

How to flatten a PDF

For forms, each field’s current appearance is drawn onto the page as ordinary content and the fillable layer is removed. For everything, each page is rendered with its form values and comments, then rebuilt as a flat image at the same size.

Add your PDF

Drop in the filled-in form or commented PDF. Altto shows what it found.

Choose what to flatten

Form fields only (sharp, searchable text) or everything.

Download the flat copy

Your file ends in -flattened.pdf. The original isn’t changed.

Tips

Flatten at the right moment

Flattening can’t be undone in the new file, so a little order helps.

Keep an editable copySave the fillable version somewhere before flattening, in case you need to correct an answer later. The tool never changes your original file.
Sign, then flattenAdd a drawn or typed signature with Sign PDF, then flatten with “Everything” so it can’t be lifted off the page.
Merging forms?Flatten each form before you merge them. Fields with the same name in different forms can otherwise end up sharing answers.
Then clean itRun the flattened file through Remove PDF Metadata if it’s going somewhere you’d rather not show your name or software.

Like every Altto tool, this runs on your device — nothing you add is uploaded. How Altto works

200

dots per inch is the resolution used when every page is flattened into an image: sharp for printing and on-screen reading, without making the file enormous.

Before and after

What changes when you flatten

A quick look at what each option does to your file.

Flatten PDF options compared
	Form fields	Everything
Form answers locked in	Yes	Yes
Comments, highlights and stamps locked in	No, left as they are	Yes
Text searchable and selectable	Yes	No, pages become images
File size	About the same	Usually larger
Works on every form	Most forms	Yes

FAQ

Frequently asked questions

What flattening does and when to use it. Want to add a signature first? Use Sign PDF.

What does flattening a PDF mean?

It merges the parts of a PDF that float on top of the page, such as form fields, comments, stamps and drawn signatures, into the page itself. Afterwards they look exactly the same but can no longer be typed over, moved or deleted, and they print and display the same in every app.

Which option should I choose?

Choose Form fields for a filled-in form: your answers become ordinary text on the page, still sharp and searchable, and the file stays small. Choose Everything if the PDF has comments, highlights, stamps or a drawn signature you want locked in too, or if the form option doesn’t work on a particular file.

Why does “Everything” make the text unsearchable?

To lock in every kind of mark-up exactly as it looks, each page is redrawn as a high-resolution image (200 dpi). It looks the same and prints crisply, but the words become part of a picture. If you need searchable text back later, PDF to Word can read it with OCR.

Why do forms need flattening before sending?

Some apps hide or lose form answers, especially on phones and when PDFs are merged or printed. Others let the recipient change the answers. Flattening makes sure everyone sees what you filled in, and that it stays that way.

Will a digital signature still be valid?

No. A certificate-based digital signature checks that the file hasn’t changed since signing, and flattening changes it. Flatten first and then sign, or keep the signed original. Drawn or typed signatures, like the ones from Sign PDF, flatten fine with “Everything”.

Is my PDF uploaded?

No. The form is flattened by PDF code running in this tab, on your device. That matters for tax forms, applications and contracts, which are exactly the files people flatten.

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