How to Edit PDF Text and Add Images or Markup

Decide what kind of edit the PDF needs

“Edit a PDF” can mean several different things. You might need to correct selectable text, add a missing date, place a logo, highlight a sentence, or draw attention to a section. Those changes are different from running optical character recognition on a scan or rebuilding a flowing source document.

The smallpdf.app Edit PDF tool directly replaces page text when the original PDF command can be mapped safely. If the command cannot be rewritten reliably, it rebuilds the affected page from its rendered appearance and adds the replacement as searchable text. The editor can also add text, dates, times, images, highlights, rectangles, lines, whiteout areas, and freehand marks.

Start with a clean, final source

Keep an untouched copy of the original PDF before you begin. Then open the document and review its page count, orientation, and current content. If pages are missing, duplicated, or out of order, correct those issues with the Organize PDF tool before adding page-level edits.

Check whether the text is selectable. A scan is usually a picture of a page, so normal text detection may not find words that can be replaced. For printed scans, choose the recognition language and run OCR on the current page. Editing a recognized block rebuilds that page: the selected source pixels are covered and the replacement text remains searchable.

Add elements deliberately

1. Choose the PDF and move to the page that needs a change.
2. Select one editing tool and place the new element near its final position.
3. Adjust its size, color, opacity, alignment, rotation, or image fit as needed.
4. Use the layer controls when elements overlap in the wrong order.
5. Zoom in to check the edit, then zoom out to confirm it still fits the whole page.

Use restrained formatting that matches the document. New text should remain legible without covering nearby labels. Images can be contained inside their box or cropped to fill it; review the result closely when cropping could remove an important edge. Highlights should remain transparent enough for the original words to be read.

Check whether a replacement is native or rebuilt

When selectable text is detected, click a highlighted block and type directly on the page. Replacement text wraps inside a fixed box; it does not move nearby document content. If the new text does not fit, shorten it, resize the box, or reduce the font size before finishing. The Properties panel identifies the replacement mode. A native replacement removes the selected page-text command and writes new searchable text, and the replacement font may use the closest safe match.

PDFs can encode text as custom glyphs, composite fonts, coincident repeated commands, or reusable objects. The editor uses rendered position to distinguish repeated text commands when their locations are unambiguous. When it still cannot identify a safe source command, it rebuilds that page at high resolution, removes its original PDF page content, covers the selected source pixels, and writes the replacement as searchable text.

A rebuilt page keeps its visible appearance, but its original selectable text and vectors become a page image. Links, annotations, and interactive form fields on that page are flattened or removed. If those features must remain live, correct the source document and export a fresh PDF instead.

Separate editing from signing

Finish content changes before placing a signature. Editing a PDF after it has been signed can create confusion about which version was approved and may invalidate existing certificate-backed signatures. When the document is final, use the Sign PDF tool if the recipient accepts visible signatures, initials, text, or dates.

If the recipient requires a particular signing provider, certificate, audit trail, or portal, follow that process instead. A visible signature and a certificate-backed digital signature can look similar but provide different evidence.

Open protected PDFs carefully

If the PDF has an open password, the editor asks for it before loading the document. The downloaded edited copy is not password protected, so protect the finished file again if it still needs access control. The editor always creates a new download and does not overwrite the source file.

Check the exact downloaded copy

Export the edited PDF under a new name rather than replacing the source. Reopen that downloaded file and inspect every edited page. Confirm that text has not been clipped, images are sharp enough, highlights remain readable, lines and shapes are in the intended layer order, and no temporary mark was left behind.

Also check page count, links, forms, attachments, and existing signatures when those features matter. PDF rewriting can affect interactive features. The final review should use the exact file you plan to share, because a correct-looking workspace is only the start; the downloaded document is the record other people will receive.