How to flatten a PDF
- 1 Drop your PDF on the box, or click browse to choose it.
- 2 Read how many form fields and comments were found.
- 3 Choose Forms and fields to keep text sharp, or Everything into images to lock everything.
- 4 Press Flatten and download.
When to flatten
Flatten filled forms before sending them, and flatten into images when comments or layers must be locked. Sign first with Sign PDF, then flatten, then shrink the result with Compress PDF if needed.
- Keep the original if you may need to change answers.
- Forms mode keeps text searchable.
- Image mode also hides text under white-out.
Features
Two flattening modes
Form fields only, or every page as an image.
Finds what is editable
Counts form fields and comments before you start.
Private
Processed on your device; nothing is uploaded.
When to use it
Submitting filled forms
Flatten an application or tax form after filling it so answers cannot be changed. To sign it first, use Sign PDF.
Printing problems
Some printers skip form fields or comments. Flattening makes sure everything prints.
Sharing final versions
Send a reviewed document with comments fixed in place. To also lower the file size, use Compress PDF.
Stopping copy and edits
Flattening into images makes it much harder to copy or change text.
Related PDF tasks
Frequently asked questions
What does flattening a PDF mean?
Flattening merges interactive parts, such as form fields and comments, into the page itself. The result looks the same but cannot be edited like a form any more.
Which mode should I choose?
Choose Forms and fields for filled forms; text stays sharp and searchable. Choose Everything into images if the PDF has comments, layers or signatures you want locked, or if a printer or website has trouble with the file.
Will the text still be searchable?
With the forms mode, yes. With the image mode, no, because each page becomes a picture. Use the image mode only when locking matters more than searching.
Why does it find no form fields?
The PDF may not have fillable fields, or the answers were typed as comments. Use the image mode to lock comments and annotations.
Does flattening reduce the file size?
Forms mode makes little difference. Image mode may make text-heavy files larger and scanned files smaller, depending on the quality you choose.
Can flattening be undone?
No. Keep the original if you might need to change the answers later.
Will digital signatures still be valid?
Flattening changes the file, so digital certificate signatures will no longer verify. Drawn signatures stay visible.
What image quality should I use?
High at 150 dpi suits most documents. Choose Print at 200 dpi for small text or documents you will print.
Is flattening the same as compressing?
No. Flattening fixes forms and comments into the page so they cannot change, while compressing makes the file smaller. You can flatten first and then compress the result if the file needs to be smaller.
Is my PDF uploaded?
No. Flattening happens in your browser, so your form answers stay private.
How this tool works. These PDF tools run entirely in your browser using two widely used open-source libraries: PDF.js, the PDF engine built into Firefox, to read and render pages, and pdf-lib to create and edit files. Each tool is tested with typed documents, phone scans and photo-heavy files before it goes live, and nothing you open is sent to a server.
Built and reviewed by Hamza Farooq, founder and lead developer
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