# Writing on a PDF

Highlight it, circle it, argue with it in the margin, and fill in its form, all inside the note, without changing the file you were sent.

By Jon C. Phillips · 31 October 2026 · https://scratchpad.sh/blog/writing-on-a-pdf/

Somebody sends you a lease.

You want to mark the clause about subletting, circle the part that worries you, and write "sixty?" next to the notice period. On paper that takes a pen and ten minutes.

On a computer it usually takes a different app. You download the file, open it somewhere else, mark it up, save a copy, and now the lease lives in your downloads folder while your questions about it live in a note.

**In Scratchpad, the PDF is already in the note, and you write on it there.**

## Opening It

A PDF in a note shows its pages in place. The expand button above them opens the reader, which covers the whole screen and has a row of tools along the top.

Each tool has a letter, so you can keep your eyes on the page.

| Tool | Key | For |
| --- | --- | --- |
| Read | **V** | Selecting words, moving marks |
| Pen | **P** | Anything by hand |
| Highlighter | **H** | The line that matters |
| Underline | **U** | A quieter highlight |
| Strikethrough | **S** | The line you disagree with |
| Text note | **T** | Words written on the page |
| Post-it | **N** | A remark that covers what's under it |
| Shapes | **R** | Boxes, stars, bubbles, and arrows |
| Eraser | **E** | Taking part of a mark, or all of it |

![A lease in the reader, with a highlighted sentence, a pen circle, a struck-out notice period, a written question, an arrow, and a post-it.](https://scratchpad.sh/assets/img/docs/pdf-marked-up.webp "One page of a lease, with six of the tools on it.")

## The Highlighter Follows The Line

This took more work than anything else in the reader, and you should never notice it.

A PDF doesn't store its words in the order you read them. The first version of the highlighter trusted that order, and my own lease broke it. A lease is a form, and in mine every label had been written before every filled-in value, so dragging across one line lit up a third of the page.

So now it looks at where the words actually sit, groups them into the lines you can see, and marks along those. Highlight, underline, and strikethrough all work this way.

A scanned page has no words to follow, so the same drag marks the box you drew.

## Everything Stays Movable

A mark isn't paint.

With the read tool, press anything you've drawn, a pen stroke included, and it picks up. You can drag it, resize it, or turn it. That goes for shapes and notes as well, so a circle that came out in the wrong place can just be moved.

Every tool that leaves a mark keeps its own colour. The chevron beside it holds the colours and sizes, so the pen can stay blue while the highlighter stays yellow.

![The highlighter's chevron open, showing ten colours with yellow selected.](https://scratchpad.sh/assets/img/docs/pdf-tools.webp "Each tool remembers its own colour.")

The eraser has two modes. **Whole** takes the mark it touches. **Part** works like a real rubber, biting a piece out of a highlight or cutting a stroke in two.

Undo and redo sit at the end of the bar, beside a button that hides every mark for a moment so you can read the page clean.

With a stylus, the pen responds to how hard you press. On a touch screen, one finger draws and two move the page, and a toggle switches that around if you'd rather only the stylus drew.

## Filling In The Form

Plenty of PDFs want something back from you.

If the file has real form fields, they work in the reader. Click one and type, or tick the box.

![The tenant details page of the lease, with its fields filled in and a box ticked.](https://scratchpad.sh/assets/img/docs/pdf-form.webp "The form inside the PDF, filled in without leaving the note.")

The download keeps them as form fields rather than flattening them, so whoever receives it can still correct a phone number.

## Bringing Words Into The Note

Marks live on the page. Sometimes what you want is the sentence itself, up in the note, next to your own thinking.

Select some words and press **Quote in note** at the top of the reader.

![A sentence selected in the lease, with the Quote in note button at the top of the reader.](https://scratchpad.sh/assets/img/docs/pdf-quote.webp "Select the words, then press Quote in note.")

They arrive as a quote under the PDF, with a link saying which page they came from.

![The note with the quoted sentence under the PDF, and a link reading From Lease.pdf, page 2.](https://scratchpad.sh/assets/img/docs/pdf-quoted-note.webp "The link opens the PDF at that page, with the words lit.")

That link is what makes it worth doing. Press it next month and the PDF opens at the page, with the sentence lit, so you can see what came before it.

## The File Stays Yours

Your marks aren't written into the PDF. They're kept in Scratchpad, beside it.

**The file you uploaded is never rewritten.**

That matters more than it sounds, because a lot of PDFs belong to someone else. The contract you were sent stays the contract you were sent, however much you've scribbled on it.

So there are two download buttons, and they do different things.

| Where | What you get |
| --- | --- |
| **In the reader** | A copy with your marks burned into the pages and the form filled in |
| **On the PDF's row in the note** | The file exactly as it arrived |

Because the marks are part of the note, a share link shows them, and **Download everything** in Settings brings them along. A Markdown export can't carry a drawing, so they aren't in that one. They also belong to this note's copy of the PDF, so the same file attached to a second note starts clean.

The details are in [reading and marking up a PDF](https://scratchpad.sh/docs/files-and-pdfs/reading-a-pdf/).

## Why In The Note

There are better PDF editors than this one. If you need to rewrite the text inside a PDF, reorder its pages, or collect signatures from four people, use one of those. Scratchpad does none of that.

But most of the time a PDF isn't something I want to edit. It's something I'm thinking about.

The lease, the quote from the contractor, the paper for Thursday's class. My questions about it, what I decided, and who I need to call all belong in the same place as the document, and that place is the note.

**You read with a pen in your hand. Now the pen is already there.**