How to Add Text to a Scanned PDF (Overlay, Not OCR)

Why a scanned PDF is different (image vs. real text)

When you scan a paper document or photograph it with a phone, the result is a PDF holding a picture of the page, not selectable, editable text. The letters you see are made of pixels, the same way a JPEG of a street sign is.

That's why you can't double-click a word in a scan and start typing over it. There is no underlying text layer to grab. Changing the original wording would require OCR (optical character recognition) to first read the pixels as characters and rebuild a text layer, a separate process our editor does not perform.

For most real tasks, though, you never need to touch the original text. Filling in a scanned form, adding a missing detail, signing, or marking something up all work by adding your own content on top.

The overlay approach: add your text on top of the image

Overlaying means placing a fresh, fully editable text box above the scanned image. Your new text lives on its own layer, so it stays crisp and adjustable while the scan underneath is left untouched.

Here is how to add text to a scanned PDF this way:

• Open the editor in your browser and load the scanned PDF. The file is processed locally on your device and is never uploaded to a server.
• Choose the add-text tool and click the spot on the page where you want to type, for example a blank line, an empty field, or next to an existing label.
• Type your text. Since an image-only page has no nearby digital font to copy, choose a clean, readable font such as a standard sans-serif.
• Adjust the font, size, color, bold or italic, and alignment so your entry lines up neatly with the printed layout of the scan.
• Move or resize the text box so it sits exactly on the line, then repeat for each field.
• Download the finished PDF when you are done.

Sign, annotate, and mark up scanned pages too

Adding text is only part of it. Because everything sits on an overlay layer, you can treat a scanned page like a printout you are filling in by hand, only cleaner. Useful tools for scans include:

• Signatures: draw your signature with the mouse or type it, then drop it onto a scanned contract or form.
• Highlight: emphasize a printed line or clause without altering the scan.
• Freehand draw, lines, and rectangles: circle a figure, underline a heading, or box an area for attention.
• Insert images or a logo: place a stamp graphic or company mark onto the page.
• Stamps and sticky notes: mark a page Approved or leave a note for a reviewer.
• Eraser: remove an overlay mark you added (it affects your annotations, not the underlying scanned image).

Filling in a scanned form, line by line

Scanned forms are the most common reason people want to type on an image PDF. Because the form's boxes are just printed lines inside a picture, none of them are clickable fields, so you fill them by overlaying text. A reliable workflow:

• Zoom in so you can place each entry precisely on the printed line.
• Add a text box for each field, name, date, amount, or checkbox area, and type your answer.
• Match the size of your text to the surrounding print so it looks like it belongs on the form.
• For checkboxes, add a short mark like an X with the text tool, or use the draw tool to make a check.
• Use undo and redo freely while you position things, then print or download the completed form.

What overlay can't do (and the honest limits)

Being clear about the boundaries keeps the experience smooth. Within these limits, the overlay method still handles the everyday jobs, typing on a scan, signing it, and marking it up, with no uploads and nothing to pay.

• It does not edit the original scanned words. To change text that is baked into the image, you would need OCR to convert it first, which this tool does not do.
• It does not redact securely. A black rectangle over sensitive info hides it visually but is not true destructive redaction, so do not rely on it for secrets.
• It is a desktop, mouse-based editor. It runs in browsers on Windows, Mac, Linux, and Chromebook, and works best with a mouse or trackpad.
• It does not convert the scan into a Word document or another format. The output stays a PDF with your overlay baked in on download.