Converts all form fields and annotations into static content. The output is no longer editable.
How it works
PDF flattening converts all interactive form fields, annotations, and markup overlays in a PDF into static visual content permanently embedded in the page. A flattened PDF looks identical to the original but the fields are no longer editable — clicking a text field produces no cursor, and checkboxes cannot be toggled.
Why flatten before distribution: interactive PDF fields can be modified after you send the document — a recipient could change the values in a signed contract. Flattening prevents this. Courts, regulatory bodies, and procurement systems often require "non-interactive" PDFs because interactive fields create ambiguity about whether the document was altered. Digital signature workflows often require a flattened base document before applying the signature.
What gets flattened: - AcroForm text fields, checkboxes, radio buttons, dropdowns - Free-text annotations, sticky notes - Drawing annotations (lines, shapes, arrows) - Highlights, underlines, strikethroughs - Comments and review markup
What is NOT changed: the text content, images, fonts, and page structure of the document body remain identical. Only the interactive overlay is merged down.
How to use it: upload your PDF and click Flatten PDF. The flattened document downloads in seconds. No configuration is needed — all field types are processed automatically.
Flattening vs printing: printing to PDF from a viewer also produces a flat PDF, but often at reduced quality (rasterized at screen DPI). This tool preserves the original vector quality by merging the form layer into the page at the PDF coordinate level.
Privacy: flattening runs entirely in the browser using pdf-lib. No data is uploaded.
Frequently Asked Questions
- Printing to PDF in a browser or system dialog rasterizes the page at screen DPI (typically 72–96 DPI), converting all vector text and graphics to pixels. Flattening with pdf-lib merges the interactive layer into the page at the original vector resolution — text remains sharp and searchable, fonts stay embedded, and file size is not inflated by rasterization. Flattening is the correct approach for distribution-quality PDFs.
- Flattening removes annotation-based signatures (drawn signatures embedded as annotation objects). Cryptographic digital signatures (X.509 certificate-based, compliant with PAdES or CAdES standards) are a different type of data and are typically invalidated by any modification to the document — including flattening. Use dedicated signature platforms (DocuSign, Adobe Sign) for legally binding cryptographic signatures that need to survive document distribution.
- No. Flattening is a one-way, irreversible operation. The interactive field data is permanently discarded. If you need to preserve the ability to re-fill or re-edit the form, keep the original interactive PDF and flatten only distribution copies. Always work from the original — never flatten your working copy.
- When form field text is merged into the page, pdf-lib may add new font subsets or content streams that slightly increase file size compared to the original. The size increase is usually small (a few kilobytes). Run the flattened PDF through the PDF Compress Preset tool afterward to recover some of that overhead.