rapier

A very fast Markdown editor in one file. Write, draw, paint and keep notes on your phone or in any browser, offline, with no account. Long documents open and scroll fast. Nothing leaves your device unless you share it.

Tip. Tap any paragraph to edit it. Drag the circle at the right edge to move through a long document, or tap it for the headings.

Contents

• Start here
• Writing
• Lists
• Pictures
• Drawing
• Paint
• Tables
• Code
• Notes
• Open, save and export
• Compare
• Agents
• Where it runs
• Keyboard
• For developers and agents
• Will

Start here

1. Tap this line to edit it in place.
   1. The formatting bar comes up with the everyday tools. Its + has every other command.
   2. You can type Markdown too; Rapier shows it formatted as you go.
   3. Tap outside the text when you're done.
2. Tap a line in the contents above to jump there. Every heading is a link, and + → Table of contents adds a line like those to any document.
3. Tick a box.
   • ☑ Open Rapier
   • ☐ Change these words
   • ☐ Tick this box
4. This guide is yours to play with. Undo is on the formatting bar if you need it.

Writing

Bold, italic, struck through, underlined, code, highlighted, 🟢green, 🔴red, 🔵blue, H₂O and 1^st. It's all plain Markdown, so other Markdown apps open the file too.^[1]

A good sentence is a place to begin.

Note. A callout is a quote that starts with [!NOTE], [!TIP] or [!WARNING]. Apps that don't know callouts show it as a quote.

Find and replace is behind the magnifier. + → Line adds a page break for PDF and Word; Footnote, Divider and Table of contents are there too.

Lists

1. A numbered list keeps its numbers as you add, move and delete lines.
2. Put the cursor in an item and tap Nest to indent it; Resume brings it back.
   1. Numbers restart inside.
   2. Bullets and numbers mix freely.
      • A bullet inside a number
      • Another one
   3. And back out again.
3. Tab and Shift Tab do the same from a keyboard.
4. A checklist is a list with boxes:
   • ☑ one you tick from the page
   • ☐ one still to do
5. Paste a list from Word or a web page and it stays a list.

Pictures

Add a picture (PNG, JPEG, WebP or JPEG XL), then drag to move or resize it. The words wrap around its outline, not its box. Tap the picture for its controls: the brush opens it in Draw, T changes its description, and you can turn it or fade it. Pictures live inside this Markdown file; nothing is uploaded. New pictures are stored as JPEG XL, which keeps them small.

Drawing

The brush on the formatting bar starts a new drawing. SVG Brush follows your pressure and speed, and a stroke that looks like a circle, box, line or arrow becomes that shape with one tap. SVG Pen (Testing) draws an even line. Tap a shape to move, resize, label or restyle it, or to bind an arrow that stays attached as things move. The drawing is saved in the file as SVG, and an agent can edit it later.

With a decorative letter, an ordinary paragraph can feel like a page from an old book. Draw has four letter sets, traced from the British Library's public scans. This W is a drawing too: tap it, then the brush, to make it your own.

Draw an SVG line, choose Select, tap the line, then Style → Look to turn it into a spring, rope or tube. For when your meeting notes need more tension.

Paint

Raster Brush opens the painting brushes: oil, bristle, marker, pencil, pen and watercolour, run by Rapier's own engine, so a MyPaint preset behaves as its author tuned it. Watercolour keeps spreading after you lift your finger, then dries. Smudge, smear, blend and erase work on paint that's already down. A painting is one picture inside the drawing, saved losslessly, and you can paint into it again.

Tables

Tap a cell to edit it; Tab moves to the next. Add or remove rows and columns from the cell's controls. Paste cells from a spreadsheet and the table grows to fit them.

Code

export function twice(x) {
  return x + x;
}

Code is highlighted offline. Text and code files open in the source editor, where the circle takes you to a line or a declaration. The eye/code switch in Settings shows the Markdown behind this page.

Notes

Open Notes from the three dots. Each note is a Markdown file shown as a card you can pin, colour and sort into sections. A note can hold a checklist you tick from its card, a reminder, a voice recording, drawings and attached files. Import brings in notes from Google Keep, Apple Notes, Evernote, Notion, Obsidian and a dozen more apps; Backup saves them all as one zip. Sync keeps them in your own Cloudflare account, encrypted with a key that never leaves your devices.

Tip. Keep a backup of notes you care about. A browser can clear its stored data; the Android app keeps notes in its own files.

Open, save and export

Open Markdown, text, code, Word, TextPack or PDF files. A Word document becomes an editable page with its pictures; a PDF comes in as text or as pictures of its pages.

Rapier keeps a draft as you work, so a closed tab comes back. Save writes the file and, where it can, reads it back to check. Your Markdown stays readable in every other app.

Under the three dots, Copy, Share and Export send your work as text, a web page, PDF or Word. A shared web page opens offline in any browser, and Rapier can open it again for editing.

Compare

Compare, under the three dots, shows what changed between this document and another file, with the unchanged parts folded away. Neither file changes.

- A first thought.
+ A better way to say it.

Agents

Use Rapier with an AI agent on the same document. Ask for an explanation, a rewrite, a plan or a diagram. It reads only the parts it needs, can't overwrite what you're editing, and its changes can be undone without losing your own. While it's connected, the circle says so; tap it for status, messages and changes. Select a passage and use Ask to talk about that part.

Try asking: “Draw how this works, then leave room for my notes.” The diagram is laid out for you, with numbered steps and arrows that find their way around the boxes, in light and dark. Every box stays a shape you can move, relabel or recolour.

Where it runs

Made for your phone, and the same in any browser: use it at rapier.website, install it as an app, or keep rapier.html on a USB stick. On Android, the Rapier app keeps your notes in its own files and never touches the internet. The whole editor is one file, under 2 MB.

Keyboard

Hold Ctrl (Cmd on a Mac), then:

Tab and Shift Tab nest a list item, indent code or move through a table. Esc closes what's open.

For developers and agents

npx rapier-html notes.md
npx rapier-html notes.md --view draw
npm install rapier-markdown-kit
npm install rapier-embed

Give someone the whole editor around their document with rapier-html, read and write Markdown with the kit, or embed Rapier in your own app. The agent tools are described in llms.txt and agents.md; the hosted connection is https://mcp.rapier.website/mcp.

Rapier is free software under AGPL-3.0-only. The Markdown kit uses the MIT licence.

Will

If you work with an agent, you can tell it what it may do with each part of a document: type an intent on a section, or lock it. Select the section and tap W on the formatting bar. Rapier writes that into the document as invisible HTML comments, which agents see when they work on it and people never do. It travels with the file: Markdown, Word, PDF and Rapier's own web pages.