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Security & Privacy

Flatten PDF Online, Free

Flatten a PDF online free so what you see is all there is: form answers, comments, stamps and drawn signatures become part of the page and can’t be changed or deleted. Nothing is uploaded.

Flatten PDF

Settings appear once you add a PDF.

Form fields Answers become plain page content that can’t be changed.
Comments, highlights, stamps and drawings
Advanced 3
Keep clickable links
Remove scripts and automatic actions
How flat

Ctrl + Enter runs it ·

Bytes sent anywhere: 0 B

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  • 100% private Your PDFs never leave this device. Everything runs in your browser.
  • No limits No file-size cap, no watermark, no sign-up and no daily quota. Free.
  • Batch ready Add as many PDFs as you like; each one is handled and saved in one go.

How to flatten a PDF online free

  1. Add your PDFs: Drop the filled form or commented PDF.

  2. Check the settings: Choose what to flatten: form fields, comments and stamps, and whether to strip scripts.

  3. Save the result: Save it. Every viewer now shows exactly the same page, and nobody can edit the answers.

Why it doesn’t upload

The PDFs people flatten are filled-in forms and signed agreements — names, addresses, ID numbers, signatures. Flattening them here keeps that data on your device instead of passing it through a stranger’s server on the way to being locked.

Check it in your browser’s Network tab

Worth knowing

  • Flattening can’t be undone in the new file. Keep the original if you might need to change an answer.
  • Links survive by default; untick Keep clickable links to flatten them too.
  • Comments without a visible appearance (some sticky notes) are removed rather than drawn.
  • “Pages to images” makes the file larger and its text unselectable — use it only when you need nothing to be extractable.

Under the hood

What happens to your file

Form fields have their current appearance drawn into the page and are then removed, so the answers can no longer be changed. Comments, highlights and stamps are drawn in from their appearance streams (ISO 32000 §12.5.5) and removed; scripts and automatic actions are deleted. The stronger setting rebuilds each page as an image, leaving nothing editable at all.

Runs on pdf-libpdf.js

Reference: ISO 32000-2 (PDF 2.0)

Why flatten a PDF before you send it?

A filled form or an annotated PDF is really two things: the page, and a layer of fields, comments and stamps floating above it. Different readers treat that layer differently — some hide it, some let anyone edit it, some print it blank. Flattening paints the layer into the page, so every viewer and every printer shows exactly what you see now, and nobody can quietly change an answer.

Flattening here happens in your browser. The filled form — often full of personal details — doesn’t pass through anyone’s server to be locked down.

Common reasons to flatten a PDF

  • Submitting a completed application form

    Lock your answers in so the recipient sees them in any viewer and can’t edit them.

  • Flattening a form before sending it to a client

    Answers, ticks and signatures are drawn into the page and scripts are removed, so the client sees exactly what you filled in and can’t change it.

  • Forms that print or upload blank

    If your answers vanish when printed or uploaded, the receiving system ignores form fields. A flattened copy fixes that.

  • Final versions of reviewed documents

    Burn approved comments, stamps and highlights into the pages so the record can’t be altered.

  • Signed PDFs

    Make a drawn signature part of the page rather than a movable annotation.

  • Making text unextractable

    The “pages to images” option turns every page into a picture when nothing should be copyable at all.

Tips for flattening PDF forms and annotations

  1. Save an unflattened copy first. Flattening can’t be undone, and you may need to change an answer later.
  2. Leave Keep text selectable on unless you have a reason not to; the file stays small and searchable.
  3. Links survive by default. Untick Keep clickable links if the final file shouldn’t lead anywhere.
  4. Turn on Remove scripts and automatic actions for files going to an upload portal; many reject PDFs carrying JavaScript.
  5. Flattening locks content but doesn’t hide it. If something must not be readable at all, redact it instead.

Questions

What does it mean to flatten a PDF?

It merges everything layered on top of the page — form fields, comments, stamps, signatures — into the page itself. The PDF looks the same, but those items can no longer be edited, moved or deleted.

How do I make a fillable PDF non-editable?

Fill it in, then flatten it here with Form fields switched on. The answers become ordinary page content, so nobody can change them before printing or forwarding.

Is flattening the same as redacting?

No. Flattening keeps everything visible and makes it permanent. Redacting removes content. To hide something, use Redact PDF instead.

Why do forms look different in different PDF readers?

Each reader draws unflattened fields itself, with its own fonts and rules. Flattening fixes the appearance once, so Chrome, Preview and Acrobat all show the same thing.

Will the text still be searchable?

Yes, in the default mode. Only Pages to images under Advanced turns pages into pictures.

Can I flatten a PDF without uploading it?

Yes. Form fields and comments are merged into the page in your browser, so a filled-in form with personal details never leaves your device.

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