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Flattening a PDF merges every interactive layer — fillable form fields, checkboxes, radio buttons, stamps, annotations and signature images — into the page content itself. The document looks identical, but the values become permanent graphics that no viewer can edit, clear or re-fill. PDFWix flattens PDFs entirely inside your browser with pdf-lib, so a signed contract or completed tax form never leaves your device.
Flattening a PDF merges every interactive layer — fillable form fields, checkboxes, radio buttons, stamps, annotations and signature images — into the page content itself. The document looks identical, but the values become permanent graphics that no viewer can edit, clear or re-fill. PDFWix flattens PDFs entirely inside your browser with pdf-lib, so a signed contract or completed tax form never leaves your device.
| Approach | Looks identical | Text stays selectable | File size | Can be undone |
|---|---|---|---|---|
| PDFWix Flatten PDF | ✓ Yes | ✓ Yes | ≈ unchanged | ✗ No |
| Print to PDF | Usually | ✗ Often rasterised | Often much larger | ✗ No |
| Screenshot each page | ✗ Blurry | ✗ No | Much larger | ✗ No |
| Password-restrict editing | ✓ Yes | ✓ Yes | ≈ unchanged | ✓ Yes, with the password |
Comparison of the common approaches to making a filled PDF uneditable.
To flatten a PDF free: open PDFWix Flatten PDF, drop in your filled form, click Flatten PDF, and download. Form fields, checkboxes, stamps and signature images become part of the page and can no longer be edited or cleared. Processing happens in your browser — the file is never uploaded.
PDFWix Flatten PDF runs entirely in the browser using pdf-lib. Flattening writes each AcroForm field's appearance stream into the page content stream and then removes the field and widget annotation dictionaries, so the values become static page graphics. Because the page content is preserved rather than re-rendered, text remains vector and file size stays close to the original — unlike "print to PDF", which rasterises pages.
A PDF can carry two separate layers. The page content layer holds the text, vectors and images that are printed. On top of that sits an interactive layer: AcroForm fields, checkboxes, radio groups, dropdowns, free-text annotations, sticky notes, stamps and signature widgets. Anything in the interactive layer is stored as a separate object with its own value, so any PDF reader can change it, clear it or re-fill it. Flattening merges the second layer into the first. Each field's rendered appearance is written into the page itself and the field object is deleted. Visually nothing changes — the same ticks, the same typed answers, the same signature in the same place — but there is no longer a field to click. That is why agencies, courts and HR teams ask for flattened PDFs: the submitted answers cannot be altered after the fact, and every viewer displays the document identically, including older readers that ignore form appearances and show completed forms as blank.
Typical flatten time: Under 3 seconds · Processing: 100% in your browser · Quality loss: None — text stays vector
Need to fill the form first? Use Fill PDF Form, then flatten the result here. To add a handwritten signature before flattening, use Sign PDF.
The fastest way to flatten a PDF on any device is in the browser: open Flatten PDF, drop the file, click Flatten PDF and download. It works the same in Chrome, Edge, Firefox and Safari, so there is nothing to install. Other methods and their trade-offs: - Windows 'Microsoft Print to PDF': flattens, but often rasterises pages, so text stops being selectable and file size can double. - Mac Preview (File → Export as PDF): keeps form values on many files, but some fields still remain editable — always click into a field afterwards to check. - iPhone and iPad: the Share → Print → pinch-to-zoom trick creates a flat copy, but quality varies; the browser tool keeps vector text. - Adobe Acrobat Pro: Print Production → Flatten, a paid option. When to flatten: after completing a…
Yes. Flattening with PDFWix is free, adds no watermark, and the flattened file downloads straight to your device.
No. The field objects are deleted and their appearance becomes part of the page, so there is nothing left to restore. Keep the filled original if you may need to edit it again.
Flattening keeps the visible signature image but drops the cryptographic signature field, so certificate-based validation no longer applies. If you need a verifiable digital signature, flatten first and sign last.
No. The page content is preserved exactly — same fonts, same layout, same position for every value. Only the interactivity is gone.
Barely. Unlike printing to PDF, PDFWix does not rasterise pages, so the flattened file is usually within a few percent of the original size.
Yes. PDFWix runs in any modern mobile browser — open pdfwix.com/flatten-pdf in Safari or Chrome and flatten straight from your phone.
Your PDF is processed inside your browser tab and never uploaded, which matters for signed contracts and tax paperwork.
Yes. Sticky notes, stamps and free-text annotations are merged into the page and their interactive objects removed, so comments can no longer be edited or deleted.
Fill the form first with Fill PDF Form, add a signature with Sign PDF, then flatten here. If you also need to stop the file being opened at all, add a password with protect PDF.