SimpleWriting

Write it yourself.

SimpleWriting is a Mac writing app. You write every word. It checks your grammar, shows the mistake, and names the rule — you make the fix.

The words are yours, start to finish.

What it does

• You do the writing. Every word on the page is yours.
• Grammar you fix yourself. It shows the mistake and names the rule. You make the correction.
• Local and private. Your notes stay on your Mac.
• Math mode. A switch in the toolbar turns a note into a math notebook — see below. Grammar check works here too.

Get it

Download SimpleWriting.app from Releases. The first time, right-click it → Open.

For grammar, open Settings (⌘,) and add any OpenAI-compatible API — base URL, model, key. It works as an editor with or without a key.

Markdown

Type Markdown and it becomes formatting: headings, bold, italic, strikethrough, code, code blocks, lists, task boxes, tables, quotes, rules, and math (KaTeX, offline). It is stored as plain Markdown and round-trips exactly. Paste Markdown and it keeps its shape.

Math mode

Flip the Note | Math switch in the toolbar to turn any note into a math notebook. It is fully offline, and your prose notes sit right beside the math (with grammar check).

• Inline math. Write $y = x^2$ in a note and it renders in place. Click it to edit the source again.
• Compute. Type $$ for a field that evaluates as you go — 2 + 2 shows = 4, \pi \cdot 3^2 shows 9\pi.
• 2D graphs & geometry (/2d). One expression per line:
  • y = sin(x) — plot a function
  • A = (2, 1) — a draggable point; circle(A, 1.5), segment(A, B), line(A, B) follow it
  • vector(A, B) or vector(3, -2) — vectors
  • polygon(A, B, C), angle(A, B, C), midpoint(A, B), perpendicular(line(A,B), C), sliders, and more
• 3D surfaces (/3d). Enter z = x^2 - y^2 or z = sin(x)*cos(y); drag to orbit, scroll to zoom.

Build it

git clone https://github.com/Isaw-w/SimpleWriting.git
cd SimpleWriting
./build.sh

macOS 13 or later.

License

MIT © 2026 Jack Crusher