Permanently merge form fields and annotations into the PDF.
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Most PDF viewers render form fields and annotations slightly differently. A PDF that looks perfect in Adobe Acrobat can show wrong fonts in Preview or misplaced checkboxes on Android. Flattening freezes the document exactly as it looks on your screen — every reader sees the same pixels. It is also how you prevent a recipient from editing the form values after you have filled them in, or deleting a signature annotation.
No. Once form fields are burned into page content, the structured field data is gone. Keep a copy of the editable original if you may need to change values later.
Usually yes, slightly — pages become image-based instead of vector. We use JPEG at 92% quality to keep the growth modest. If you need smaller output, run Compress PDF afterwards.
Flattening invalidates digital signatures by definition — you are modifying the document. If the signature is legally required to remain valid, do not flatten. Use the Protect PDF tool to prevent further edits instead.
No, because the text is rendered into the page image. If searchability matters, flatten before OCR, or skip flattening.
Privacy: Flattening renders pages through PDF.js and rebuilds the output with pdf-lib — all inside your browser. No upload, no server-side rendering.