Flatten PDF
Flattening turns interactive parts of a PDF, such as form fields and comments, into ordinary page content that can no longer be edited. Choose a standard flatten that keeps text selectable, or a full flatten that turns every page into a picture. Everything runs on your device.
Runs in your browser. Your files are never uploaded.
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How to use Flatten PDF
- Choose a PDF. The tool shows how many form fields and comments it contains.
- Pick Standard to flatten form fields while keeping text selectable, or Full to rasterise every page, which also bakes in comments and markup.
- For Full mode, choose a quality level. Higher quality looks sharper but makes a larger file.
- Press Flatten PDF, compare the before and after size, and download the result.
Why flatten a PDF
An interactive PDF can behave differently depending on who opens it. A form you filled in may show blank boxes in a phone preview, a field may print without its text, and a recipient can change your answers. Flattening removes that variability by making the current appearance permanent.
Typical reasons include sharing a completed form that should not be altered, archiving a finished document, preparing a file for a printer or an upload portal that rejects interactive content, and fixing form fields that do not print.
Choosing the right mode
Use Standard when you only need filled-in form fields locked down. It is quick, keeps the file size close to the original and preserves selectable text, which helps accessibility and search. Use Full when the document also carries comments, stamps, highlights or drawn markup that you want baked in, or when you want the strongest guarantee that content cannot be edited.
- Fill the form first, then flatten, because the current values are what get baked in.
- In Full mode, 144 dpi suits most documents; choose 216 dpi for small print or diagrams.
- Text-heavy files usually grow in Full mode, since text is replaced by pixels.
- Keep an unflattened original for future edits.
Limits to know about
Flattening is not security. A flattened Standard file still contains its text and structure, and anyone can still add new content, remove pages or copy text. Even a Full file can be recognised with optical character recognition. If you need to prevent changes by recipients, combine flattening with a password in a dedicated protection tool, or share a signed copy.
Very large pages are rendered at a capped pixel count to protect your browser memory, so extremely big posters may come out slightly less sharp than the setting suggests. Forms built with XFA are not supported. Everything happens locally, so no file is uploaded.
Why use this flatten pdf tool
- Two flatten modes. Standard merges form fields into the page and keeps real text. Full renders every page as an image so nothing interactive survives.
- Before and after size. A size comparison shows the effect straight away, because rasterising can make a file larger or smaller depending on its content.
- Field and comment counts. See how many form fields and annotations the file holds before you decide which mode you need.
- Works offline in the browser. Pages are processed by your own device, so confidential documents are never sent anywhere.
Frequently asked questions
What is the difference between Standard and Full?
Standard flattens form fields only. The page keeps its text, so it stays searchable and selectable, and file size barely changes. Comments, highlights and sticky notes are left as they are. Full draws every page, including annotations, onto an image and rebuilds the PDF from those images. It locks everything in, but text can no longer be selected or searched and the file is often larger.
Why would a form not print properly before flattening?
Some viewers and print drivers skip form-field widgets, or draw them with different fonts or without their values. Flattening writes the values into the page itself, so every viewer and printer sees exactly the same thing.
Can I reverse flattening?
Not in the saved file. Once the fields are merged into the page, the values are just drawing instructions or pixels. Keep your original file if you might need to edit the form again.
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