pdfcosmos

Flatten PDF

Bake form fields, comments, and stamps into the page, entirely in your browser.

Free, fast, and privacy-first.

Flatten your PDFs

or drag & drop files here

PDF files onlyup to 30 filesup to 100 MB each300 MB total

Flatten a PDF free, in your browser

Flattening a PDF bakes its interactive parts into the page itself. A form someone filled in stops being a form and becomes a finished document; comments, highlights and stamps stop floating above the page and become part of it. That is what you want when you are sending a completed form back, archiving a signed-off document, or making sure the markup someone added actually appears when the file is printed or opened in a different reader.

It is worth knowing that “flatten” means four different things, which is why searching for it returns such contradictory advice. It can mean flattening form fields, flattening annotations, merging optional-content layers (OCG), or transparency flattening for a commercial print workflow. This tool does the first two — the ones most people actually mean — and it does not touch layers or transparency, which need prepress software.

The result stays a proper PDF. Nothing is rasterized, so field values and annotation text are written into the page as real text that you can still select, search and copy, and the file stays sharp at any zoom. What you lose is the interactivity: there are no fields left to click into, which is exactly the point. That also means flattening is not redaction — the values are readable page content afterwards, so anything genuinely sensitive should be redacted first.

There are no settings to get wrong. Add up to 30 PDFs, press the button, and everything runs locally through a WebAssembly build of qpdf — one file comes back as a flattened PDF, several as a ZIP. Your documents are never uploaded, which matters when the thing you are flattening is a signed contract or a completed application form.

  • Fields become permanent

    A filled form stops being fillable — values are baked into the page.

  • Text stays selectable

    Nothing is rasterized, so the result stays searchable and sharp at any zoom.

  • Up to 30 files at once

    One PDF comes back as a PDF, several as a single ZIP.

  • Nothing is uploaded

    qpdf runs in your browser. No file data leaves your device.

How to flatten a PDF

  1. Add your PDF(s)

    Drop one file (or up to 30) into the upload area.

  2. Flatten

    Form fields, comments, and stamps are baked into the page so they can't be edited or filled.

  3. Download

    Click the button. One file downloads as a PDF, several as a ZIP.

Frequently asked questions

Are my PDF files uploaded to a server?
No. Flattening happens entirely in your browser using WebAssembly (qpdf). Your file never leaves your device. You can confirm it in your browser's Network tab: no file data is sent.
What does flattening do?
It merges annotations and interactive form fields into the page content. After flattening, form fields, checkboxes, and stamps become part of the page. They can no longer be edited or filled in.
When is that useful?
To finalize a filled-in form so its values can't be changed, to make sure comments and stamps always print, or to share a form that shouldn't be edited further.
Which kind of flattening is this?
“Flatten” is used for four different things, which is why the word causes so much confusion. This tool does the two most commonly asked for: baking interactive form fields into the page, and baking annotations (comments, highlights, stamps, drawn shapes) into the page. It does not merge optional-content layers (OCG), and it does not do transparency flattening for print production — those are separate operations that need prepress software.
Will the text still be selectable and searchable?
Yes. Flattening does not turn your page into a picture. The field values and annotation contents are written into the page as real text, so you can still select, search, and copy them afterwards, and the file stays sharp at any zoom. Nothing is rasterized.
Can a flattened form be edited or filled again?
Not as a form. The interactive fields are gone, so there is nothing left to click into or type in, which is the point. Be aware this is not the same as redaction: the values are now ordinary page content and can still be selected and copied like any other text. To remove information so it cannot be recovered, use a dedicated redaction tool before flattening.
What happens to a digitally signed PDF?
Flattening modifies the page content, and any change to a signed PDF invalidates its digital signature — that is how signatures are designed to work. If a document carries a certificate-based signature you need to keep verifiable, do not flatten it. Flattening is fine for a drawn or image-based signature, which is just an annotation.
Does flattening make the file smaller?
Usually a little, because the interactive form structure and separate annotation objects are removed, but it is not a compression tool and the saving is often modest. If size is what you are after, use our Compress PDF tool instead.
Does it work on forms made by Acrobat or LibreOffice?
Yes. Those tools often save a form without stored field appearances, marking the file so the viewer draws the values itself. Many flatteners either refuse that file or flatten it to blank boxes. We generate the missing appearances first, so what you see on screen is what gets baked into the page.
Why did I get “Couldn't process the PDF”?
The most common cause is a password-protected file: the PDF has to be unlocked before its contents can be changed. Run it through our Unlock PDF tool first, then flatten the result. The same message also covers a damaged or malformed file, which our Repair PDF tool can sometimes rebuild.
Can I flatten several PDFs at once?
Yes. Add up to 30 PDFs. One file downloads as a flattened PDF, and two or more download together as a single ZIP.
Is Flatten PDF free?
Yes, it's completely free to use, with no sign-up and nothing to install.