Flatten PDF

To flatten a PDF means to merge all of a document’s layers, including annotations, into a single layer, simplifying its structure. This way, the content is presented as a single, uneditable image, and people who view the file won’t be able to edit its elements.

PDFs are flattened to protect the documents’ layouts and keep their contents from being modified or tampered with. Aside from important business paperwork, layouts for design projects are also usually flattened to keep them secure from unauthorized edits.





Since to flatten a PDF basically means simplifying its structure into a single layer, documents are then easier to store, share, and view on different devices and platforms.

While flattening and compressing a PDF may sound similar, they are two different processes with distinct purposes.





To flatten a PDF means merging a document’s layers into a single, flat, and uneditable layer, while compressing a PDF optimizes its different elements to make the file size smaller. Images may be downscaled, non-crucial metadata may be removed, and more efficient coding methods may be applied during file compression. However, the document’s original structure remains intact.





Unlike a flattened PDF, the interactive elements within a compressed PDF will still work. That means it will continue to have interactive and, therefore, modifiable elements.





Therefore, compressing PDFs is best for submitting documents that are still subject to review or approval, while flattening PDFs are best done after files have been completed and finalized.