# Markup

> A free tool for marking up screenshots with arrows, boxes, numbered pins and text before
> sending them to an AI model, so the model knows exactly which part of the image is being
> discussed. It runs in the browser or as a standalone macOS app. Everything runs on the
> user's own machine: no upload, no account, no analytics.

Markup exists because a model reads a whole screenshot at once and cannot tell which element
a question refers to. Phrases like "the button" or "the second row" are ambiguous on a dense
interface. A red arrow or a numbered pin removes the ambiguity, and numbered pins give the
prompt a vocabulary: "1: the heading wraps. 2: this button is the wrong height."

How it is used: copy a screenshot to the clipboard, press Cmd/Ctrl+V on markup.simplicated.dev, draw
the marks, press Enter to copy the flattened PNG back to the clipboard, paste it into ChatGPT,
Claude, Gemini, Copilot, Perplexity or any other model that accepts images.

Desktop: a free, signed macOS app at https://github.com/twotimessomething/markup/releases/latest
wraps the same files, so it works with no internet connection. Closing its window leaves it
running in the menu bar; quitting is a separate, explicit action.

Tools: arrow (A), box (B), free draw (P), text (T), numbered pin (N, auto-advances), eraser (E),
undo (Cmd+Z) and redo (Shift+Cmd+Z), five annotation colours, copy (Cmd+C or Enter), and a
light/dark theme. Annotations are drawn at the screenshot's native resolution.

Privacy: the page has no backend. Images are decoded and annotated on a canvas in the tab and
never transmitted. The only stored data is one localStorage key, `markup-theme`. No cookies,
no analytics, no third-party requests.

## Pages

- [Markup (the tool)](https://markup.simplicated.dev/): The app itself. Paste a screenshot and annotate it.
- [About and FAQ](https://markup.simplicated.dev/about): What it does, why marked-up screenshots get better answers, the tool list, and nine common questions with answers.
- [Guide: how to mark up a screenshot for an AI model](https://markup.simplicated.dev/guide): Which mark suits which kind of question, prompt patterns to pair with the marks, and common mistakes.
- [Privacy](https://markup.simplicated.dev/privacy): What the page stores and what it does not.