How to edit a PDF: add text, sign and correct mistakes
By the fullpdftools team · Updated
Quick answer: open the file in a PDF editor to add text, signatures, highlights, shapes and images, or to delete and add pages. Existing text can’t be retyped in place because a PDF stores positioned text rather than paragraphs; cover it with whiteout and type over it, or convert to Word for big rewrites. To hide sensitive information for real, flatten the pages when you download, because a box drawn over text does not delete it.
PDFs are designed to look the same everywhere, which is exactly why they are awkward to change. Unlike a Word document, a PDF doesn’t contain flowing paragraphs; it records where each piece of text and each image sits on the page. Knowing that makes it much easier to pick the right approach for what you want to do. That includes how to sign a PDF, and how to redact PDF files properly instead of just covering the text.
What is easy to do
- Fill in blanks. For a flat form (one without fillable fields), place text boxes on the lines with the PDF Editor. Use a standard font at 10–12 pt so it looks like the printed text.
- Sign a document. Draw your signature once, place it on the signature line and resize it. Scale it so it looks natural, not oversized.
- Mark up. Highlight passages, circle items with an ellipse, and point at things with arrows for review comments.
- Add a logo or stamp as an image, and delete or add whole pages.
What is harder
Changing the existing wording. Because the text isn’t stored as a paragraph, there is nothing to “reflow”. The usual fix is to cover the old text with a whiteout box (matching the page colour) and type the new text on top. This works well for a changed date or figure. For extensive rewriting, it is easier to convert the PDF to Word, edit it there and convert it back — see what converts well.
Scanned documents. A scan is a picture of a page, so you can add to it but not edit the printed words.
Covering text is not deleting it
This is the most common privacy mistake with PDFs. A black rectangle or whiteout box drawn over text only hides it visually. The original text is still in the file, and anyone can select, copy or search it. News stories have repeatedly shown “redacted” documents whose blacked-out passages could be copied out.
To remove information for real, the page must be turned into a picture so that the hidden text no longer exists. In our editor, tick Flatten pages to images when you download. After flattening you can no longer select text, so keep your unflattened original for your own records, and check the result by trying to search for the hidden words.
A tidy editing workflow
- Delete pages you don’t need, or extract just the ones that matter.
- Make your edits: text, highlights, signature.
- Zoom in and check alignment, especially text placed over lines.
- If anything sensitive was covered, flatten when you download.
- Optionally compress the result, and add page numbers if needed.
Legal and ethical notes
Edit only documents you own or have permission to change. Altering someone else’s contract, certificate or invoice can be fraud. When you add a signature to a document, make sure you understand what you are agreeing to; a drawn image of a signature is not the same as a certified digital signature, which some processes require.
Frequently asked questions
Can I edit the existing text in a PDF?
Not directly in most free tools. Cover the old text with the Whiteout tool and type the new text on top, or convert the PDF to Word for larger changes.
How do I edit a PDF for free?
Open the PDF Editor, add text, highlights, shapes, images or a signature, and download the edited file. No account is needed.
How do I permanently remove text from a PDF?
Cover it, then tick Flatten pages to images when you download. Flattening turns the pages into pictures so the hidden text no longer exists in the file.
Can I edit a scanned PDF?
You can add text, signatures and marks on top, but not change the printed words, because a scan is a picture of the page.
Can I fill in a PDF form that has no fillable fields?
Yes. Place text boxes on the lines with the PDF Editor, using a 10 to 12 pt standard font so it matches the printed text.
Tools used in this guide
PDF Editor
Add text, drawings, highlights, shapes, images and signatures to a PDF.
PDF to Word
Convert PDFs to editable Word (.docx) documents.