Flatten PDF
Lock form fields, comments and annotations into the page permanently so the PDF cannot be edited further. Ideal for archiving or printing — processed locally in your browser.
or drop files here
Tip: select a single file.
How to use Flatten PDF
- 1Click "Select PDF file" and choose the PDF containing form fields or annotations you want to flatten.
- 2Confirm the pages or elements to flatten — form fields, comments, or all annotations.
- 3Click Flatten PDF. The flattened document is written locally and downloaded.
Why use PDF Lab
- Permanently embed form fields and annotations into the page content.
- Files stay on your device — nothing is uploaded to any server.
- No account, no signup, no watermark on the output.
- Free to use with no per-file limits beyond your device's memory.
- Works on desktop and mobile browsers, including offline after first load.
- Prevents further editing of form data after a PDF has been filled out.
- Ensures consistent rendering across all PDF viewers.
Your file never leaves your browser
Flatten PDF runs entirely on your device using pdf-lib and pdf.js — both self-hosted by PDF Lab, so no third-party CDN sees your traffic. There is no upload, no account, no log of your file.
How browser-based PDF processing works →Flatten PDF — questions
- No. Every operation runs in your browser using JavaScript. Your file is loaded into your browser's memory, processed, and a result is saved to your device. Nothing is sent over the network.
- No. Because the processing happens in your browser, neither PDF Lab nor any third party has access to the file contents. You can verify this by opening your browser's network tab while using the tools — no file data is transmitted.
- There is no enforced limit, but performance depends on your device's memory. Most modern browsers comfortably handle PDFs up to about 100 MB. Very large files may slow down your browser tab.
Are my files uploaded to your server?+
Can PDF Lab see the contents of my files?+
Are there file size limits?+
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