How to add text to a PDF (and why editing existing text is harder)

A form arrives as a PDF and it is not fillable. A contract needs a date written in. A diagram needs a label. All you want to do is type on the page, and it is genuinely surprising how hard some software makes it.

Two jobs that look identical

Adding text puts new characters onto the page, on top of what is there. Editing text changes characters that already exist. The first is easy and the second is hard, and almost every complaint about PDF editors is really a collision between the two.

Adding text

1. 1Open Add Text to PDF and drop your file in.
2. 2Click where you want the text and type.
3. 3Set the size and colour so it sits properly against what is already on the page.
4. 4Download.

This covers most of what people want from a PDF editor: filling in a form that was never made fillable, adding a date or a reference number, labelling a figure, correcting a detail without going back to whoever produced the original.

Why editing existing text is hard

It is worth understanding, because it explains why the tools that promise it are unreliable rather than merely lazy.

A PDF does not store paragraphs. It stores instructions to draw specific characters at specific coordinates, in a specific font, and the font itself is usually subsetted — only the characters the document actually uses are embedded. There is often no space character at all; the gaps between words are produced by moving the drawing position.

So changing one word means finding which drawing instructions correspond to it, having a font that contains the letters of the replacement (which the subset may not), and repositioning everything after it on the line. If the new word is longer, the line has to reflow — and the file has no idea where the line, the paragraph or the column ends, because it never recorded them.

Editors that do this work by reconstructing a guess at the structure and rewriting the page from it. On a simple document that works well. On a complex layout it moves things that should not have moved, and the failure is often not visible until later.

What to do instead

• If you have the original — the Word file, the design file, the source — edit that and export again. Always the right answer when it is available.
• If the change is small, cover and retype. Draw a white box over the old text and type the new text on top. It is crude, it works, and it is honest about what it is doing.
• If you need to rewrite substantially, convert it to Word, edit there, and convert back. Expect the layout to shift; the guide to PDF to Word covers what survives.
• If the text must be removed rather than replaced, that is redaction — a white box hides text that is still selectable underneath it.

If it is really a form

Check first whether the PDF has real form fields — click where a value should go, and if a cursor appears in a box, it does. Fill PDF Form handles those properly, and values typed into real fields stay editable and export cleanly. Filling in a PDF form without printing it covers the whole thing.

If there are no fields — which is the common case for a form somebody scanned — typing text onto the page is exactly the right approach, and the result prints identically.

If what you need is a signature

Typing your name in a script font is not the same thing as signing, and most recipients can tell. Sign PDF lets you draw a signature or place an image of one, which looks like what it is. How to sign a PDF covers when a drawn signature is sufficient and when it is not.

Making added text look like it belongs

• Match the size of the surrounding text rather than guessing. Zoom in and compare against a nearby line.
• Use black unless the document is not black. Pure black on a scanned page can look pasted on, because the scan's black is usually a dark grey.
• Line up with what is around it. Text sitting a millimetre above the ruled line of a form is the thing that gives it away.
• Print a test page if the document is going to be printed. Screen and paper disagree about small text more than you would expect.

Common questions

Can I edit the text that is already in my PDF?

Not with this tool, which adds new text on top. Changing existing text means rebuilding the page's internals, which no browser tool does reliably — the section above explains why. Cover and retype for small changes, or go back to the original document.

Will the text I add be selectable and searchable?

Yes. It is added as real text with a real font, not as an image of text, so it can be found, selected and copied like anything else on the page.

Can I move text after I have placed it?

Before you download, yes. Once the PDF is written the text is part of the page, so repositioning means starting again from your original — which is never modified, so that costs you nothing but the retyping.

Does it work on a scanned document?

Yes, because it does not need to understand what is on the page — it draws on top of it. If you also want the scan itself to be searchable, make it searchable first, then add your text.

Which fonts can I use?

The standard PDF fonts, which every viewer on every platform can display without embedding anything. That is a deliberate limit: it guarantees the text looks the same everywhere, which for a date written onto a contract matters more than typographic choice.

Is my file uploaded?

No. The page is drawn and the new PDF written inside your browser, so it works with the network switched off.