Flatten a PDF

Bake form fields and annotations into the page so they can’t be changed.

or drop it here · it never leaves your device

Processed in your browser. Your files are never uploaded. Check it yourself

How to flatten a PDF

A filled-in PDF form is still a form: anyone who opens it can type over your answers. A reviewed PDF is still marked up with comments that can be moved or deleted. Flattening takes what you see on the page, the typed text, the ticks, the highlights and the notes, and makes it part of the page itself, so it can no longer be edited as a field or an annotation.

It is the usual last step before you send a completed form, archive a signed copy or share a reviewed document, and it is done in your browser, so the contents of the form are never uploaded. If you need to edit it again, keep your editable original.

1
Open the PDF and read the counts
Press Choose a PDF or drop the file on the panel. A preview of the first page appears, with chips underneath: the number of form fields, the number of annotations, and a note if the file has a signature field. These come from a quick scan done on your device before you change anything.

Password-protected files ask for the password first and are unlocked in memory; the flattened copy is saved without a password.
2
Choose what to flatten
Three choices sit in the options panel. Forms and annotations bakes in everything. Forms only turns fields into plain text, ticks and choices, and leaves comments editable. Annotations only turns highlights, notes and drawings into part of the page, and leaves form fields live. The tool picks a sensible default from what it found: forms only when there are fields and no comments, annotations only for the reverse, both otherwise.

Each choice shows how many items it covers. If you select a kind that is not in the file, the Flatten button is disabled and the hint says “Nothing of that kind was found in this file.”
3
Press Flatten PDF
A progress bar runs while the file is rewritten. When it finishes, the report lists how many form fields and how many annotations were flattened, and a line for each thing that was deliberately left alone, such as signature fields. A kind you did not choose is shown as “Left as they were”; a kind that was not present is shown as “None found”.
4
Check the first page and download
A preview of the first page of the new file sits at the bottom of the result card. Compare it with the original: it should look the same. Download yourfile-flattened.pdf. Your original is never changed, so keep it if you may need to edit the form again. The card also offers Compress, Protect and Merge as next steps.

Flatten PDF features

Flatten form fields, annotations or both
Counts the fields and annotations it finds before you start
Keeps exactly what you see on the page
Leaves signature fields alone and tells you so
A report of what was flattened
Previews the first page

Flattening a PDF without uploading it

Your file is read into this browser tab and flattened by code running on your device. Nothing is uploaded.

For each form field or annotation, its on-page appearance is drawn into the page’s own content, and the interactive object is removed. The page looks the same, but the field is now just ink. Text typed into a field becomes plain text on the page, and a highlight becomes a coloured area.

Signature fields are left as they are. Changing a signed file can invalidate the signature, so those fields aren’t touched, and the report says so.
Flattening is one-way. You can’t get the fields back from the flattened copy, so keep the original.
Links are not counted among the annotations flattened here and keep working.
It’s not redaction. Flattened text is still text. To remove content, use Redact PDF.

How to prove your file never left your device: a two-minute Network-tab and offline test you can run on this tool.

Worked example

Sending back a completed tenancy form

You’ve filled in an eight-field application form and signed it with a typed signature. If you send it as it is, the agent’s software could let someone change a field. Open the form here: the scan finds 8 form fields and 1 annotation. Leave Forms and annotations selected and press Flatten PDF.

The report says 8 fields and 1 annotation were flattened. Download application-flattened.pdf. It looks exactly the same, but the fields can’t be edited any more.

Good to know

Flatten after you have finished filling in and checking, not before. You can’t edit the fields afterwards.
Building a form rather than finishing one? Create a form adds the fields that Flatten later fixes in place.
If a form looks blank after flattening, it was probably not filled in, or the answers were in a layer the viewer hid. Open the original and check.
Flatten forms before you redact. Form values are stored separately from the page text, and flattening puts them on the page where a redaction box can reach them.
Flattening can make a file a bit larger or smaller. Use Compress PDF if you need it smaller.

What “live” and “flat” mean inside a PDF

A PDF form field is not part of the page. It is a separate object, a widget annotation, that sits on top of the page and holds a value. When you type your name into a box, the value is saved in the field, and a small saved drawing called an appearance stream tells readers how to display it. A reader can show the field because it is an object; it can let you edit it for the same reason.

The same is true of comments. A highlight is an annotation on top of the page, with its own colour, position and text. It is not in the page’s drawing instructions.

Flattening takes each such object’s saved appearance, draws it into the page’s own content, and then deletes the object. The page looks the same. What has changed is its nature: before, “Jane Smith” was the value of a field that a reader could let you retype. Afterwards it is ink on the page, like text typed in the original document.

Two practical effects follow:

Nothing is left to click. Fields can no longer be selected, tabbed between or changed, and annotations can no longer be moved or deleted in a reader.
The look is fixed. A form that was missing the saved drawings, relying on the reader to draw the values itself, can come out blank when flattened, so always check the preview.

When flattening is the right last step

Good reasons

Sending a completed form. Fix the answers in place before they go to an agent, a council or an employer.
Archiving. A record whose fields still respond to clicks can change by accident when someone opens it. Flat records stay as they were.
Making a reviewed file universal. Some phone apps, printers and converters ignore annotations. Flattened marks become page content and print and display everywhere.
Before redaction. Form values are stored apart from the page text. Flatten first so that a redaction box can reach them.
Reducing the interactive surface. A flat file has no fields or comment objects to trip up a strict upload portal.

Reasons to wait

The form is not finished, or someone else still needs to fill in their part.
You want reviewers to be able to reply to or resolve your comments.
You are about to sign it. Fill in and flatten first, then sign last, as the tool order for a signed final version.
You need the data. Once fields are flat, programs that extract form data from a PDF find nothing.

Forms and annotations: what is covered and what is not

Item	Covered by “Forms”	Covered by “Annotations”	Notes
Text fields, ticks, radio buttons, drop-downs	Yes	No	Become plain text and marks on the page
Highlights, underlines, strike-through	No	Yes	Become coloured areas on the page
Sticky notes, text boxes, pen strokes, shapes	No	Yes	Sticky note icons become fixed icons; the note text is no longer reachable
Signature fields	Left alone	No	Altering a signed file can invalidate the signature, so the tool leaves them and says so
Links	No	No	Not counted as annotations here; they keep working

The counts shown before you flatten use the same split: fields are counted as form fields, and comments and markup are counted as annotations. If a count seems low, check whether the items are really something else, for example links, which are not included.

Other ways to flatten, and how they differ

Method	What it does	Catch
Print to PDF from a browser or operating system	Writes a new PDF of the page as displayed, which usually brings form values and markup in as page content.	Tends to drop bookmarks, tags and sometimes links, and changes fonts and metadata. You get less control.
Adobe Acrobat Pro	Has flatten options in its print production tools, and a “Flatten” step when exporting or combining.	Paid edition only.
Apple Preview	Can export a file in a way that fixes some annotations into the page, depending on version and options.	Results vary; check the result with another reader.
Word or Google Docs	Not applicable: they edit documents, not PDF forms.	Exporting from the source after typing answers into it produces a flat PDF by default.
This tool	Lets you flatten forms, annotations or both, keeps the rest of the file as it is, and reports what changed.	Leaves signature fields alone; one-way.

The advantage of a dedicated flattener over printing is selectivity and fidelity: you can flatten comments but keep fields live, and the document’s structure is not rebuilt from a printed image.

Three worked examples with numbers

These use round figures to show the decisions. They are not measurements.

A completed 4-page application form

The scan reports 24 form fields and no annotations. The default is forms only. Flatten: the report says 24 fields flattened. Open the result and press Tab: nothing is highlighted, because there are no fields. Type into a box: nothing happens. The answers are in the page.

A reviewed report with comments

A 20-page report has 9 highlights, 7 sticky notes and 2 rectangles, and no form fields. The scan reports 18 annotations and the default is annotations only. After flattening, the report says 18 flattened. Sticky notes now show as fixed icons with no text behind them, so if you need the comments’ text, copy it out of the original first or keep that file.

A form with a signature box

A tenancy agreement has 6 text fields, 2 ticks and one signature field already signed. The scan chip says “Has a signature field”. Flatten with forms only: 8 fields are flattened and a line in the report says signature fields were left as they are. Even so, because the file is rewritten, treat the output as unsigned and keep the signed original for the record.

Limits and edge cases

One way. There is no unflatten. If you will need to edit the form later, keep the original.
Forms that depend on scripts. Some PDF forms calculate or show values with JavaScript. What is flattened is the displayed appearance. Check the preview for totals and conditionally shown fields.
XFA forms. Some government forms use a different, older form technology (XFA) rather than the standard kind. If the scan finds no fields in a form that clearly has some, that may be why. Fill and print it from the program it was made for.
Searchability. Whether flattened values can be searched or copied depends on how the form stored them. Test with Ctrl+F in your reader, or extract with PDF to text.
Accessibility. Screen reader users interact with real fields. A flattened form gives them text to read but nothing to fill, which is right for a finished document and wrong for a blank one.
File size. Flattened files are often a little smaller as the interactive objects go, but the drawings are added to the page, so the change is not predictable. Compress afterwards if you need to.
Digital signatures. Rewriting a file changes the bytes that signatures cover. Signature fields are left in place but should not be relied on in the output.

Privacy: form answers are some of the most personal text you handle

Completed forms hold names, addresses, dates of birth, bank details and signatures. The values are read, drawn into the page and written out entirely inside your browser tab. They are never sent to a server, and the preview image of the first page is rendered locally as well.

To watch it happen, open the Network tab, load a form and flatten it. The verification guide explains what to look for and includes a version that works offline.

Flatten PDF: troubleshooting

The Flatten button is greyed out: The choice you made has nothing to flatten in this file. Look at the counts under the preview and pick the kind that has some, or accept that the file has nothing interactive.
The form looks blank after flattening: The values may have been displayed by the reader rather than saved with the field, or the form was never filled. Open the original and check. If the values show there but not in the flattened copy, print the filled form to PDF instead.
Fields are still editable in the flattened file: You may have chosen Annotations only. Run the output through again with Forms only or Forms and annotations. Also check that you opened the new file.
Comments are still visible but I cannot read their text: Flattened sticky notes become fixed icons and the note text is no longer reachable. Keep the original, or copy the comment text out before flattening.
“Signature fields were left as they are”: That is by design. The tool does not alter signature fields. The rewritten file will still not validate as signed, so treat it as unsigned.
The scan says no form fields but the form clearly has boxes: The boxes may be from an older form technology (XFA), or they may be drawn lines on the page and not real fields. Use Edit and fill to type onto the page instead.
A link stopped working: Links should not be touched by flattening. Check that you were not looking at a button field, which counts as a form field and is flattened.
“This PDF needs a password”: Enter the password at the prompt. The flattened copy is saved without one; add a new one with Protect PDF.
Totals or calculated fields show the wrong numbers: Those values were computed by a script in the reader and only the last displayed value is fixed. Recalculate in the original program, save, and then flatten.

Glossary

Flatten: To draw the appearance of form fields or annotations into the page and remove the interactive objects.
AcroForm: The standard PDF form system: a list of fields, each with a value and an appearance.
Widget: The on-page annotation that displays a form field.
Appearance stream: A saved drawing that shows how a field or annotation looks.
XFA: An older XML-based form technology used by some government and bank forms. Different from standard fields.
Signature field: A form field that holds a digital signature or marks where to sign. Left alone by this tool.
Annotation: A comment or markup object laid over a page, such as a highlight or sticky note.
Interactive: Able to be clicked, typed into or moved in a reader. Flat content is not.

Flatten PDF: frequently asked questions

What does flattening a PDF mean?

It merges interactive things, such as form fields and annotations, into the page itself. They stay visible but can no longer be edited, moved or deleted.

Can I undo flattening?

No. The fields are gone from the flattened copy. Keep your original if you might need to edit the form again.

What is the difference between forms and annotations?

Form fields are the boxes you type in, tick or choose from. Annotations are comments and markup, such as highlights, notes, drawings and stamps added with a reader.

Why does flattening stop people changing a form?

Because the answers are no longer fields. A reader has nothing to type into. Someone with an editor could still redraw the page, so flattening deters changes without making them impossible.

What happens to signature fields?

They are left alone. Altering a signed document can break the signature, and the report will say that signature fields were not flattened.

Is my form uploaded?

No. Flattening happens in your browser. The answers you typed never leave your device, which you can check yourself.

Will links still work?

Yes. Link annotations are not counted among the annotations flattened here and are left as they are.

Why is the Flatten button greyed out?

The scan found nothing of the kind you selected, such as no form fields in a plain document. Choose another option, or the file doesn’t need flattening.

Is flattening the same as making a PDF read-only?

Not quite. Flattening removes the interactive parts, so there is nothing to edit in a reader. A password with restricted permissions, from Protect PDF, is a separate way to discourage edits. Neither stops a determined person with an editor.

Should I flatten before or after signing?

Before. Fill in and flatten the form, then add your signature last. Flattening a signed file rewrites it and breaks the signature.

Will flattening make my file smaller?

It might, as interactive objects are removed, but the drawings are added to the page, so it can also grow slightly. Use Compress PDF if size matters.

Can I flatten only some pages?

Not in this tool; it works on the whole file. To flatten part of a document, split it with Split PDF, flatten the part, and merge the parts again.

Page updated 25 October 2026 · By the PDFMagpie team