Pro · one-time purchase

Edit in the rendered view, or in the source. Your choice.

A WYSIWYG editor for Markdown, a clean source editor for everything, snippets with tab stops, crash-recovery autosave, and a prompt before anything of yours is overwritten.

The short version

Twain Pro turns the viewer into an editor. Edit Markdown directly in the rendered view the way Typora made familiar, or drop to a fast source editor when you want the exact text. MDX stays source-edited with live preview, deliberately: a WYSIWYG pass over components is how documents get mangled.

Editing that respects the file

Everything here is designed so no edit, yours or an agent's, is ever silently lost.

in place

WYSIWYG editing Pro

Edit in the rendered view and see formatting as you type. For plain Markdown, where in-place editing can be trusted.

source

Source editor Pro

A clean, fast raw editor for when you want to see and control the exact text. MDX edits happen here, with live preview.

faster drafting

Snippets and templates Pro

Built-in snippets for tables, callouts, frontmatter, Mermaid and MDX, your own snippets in JSON, tab-stop insertion, and New from Template document starters.

never lose work

Autosave and recovery Pro

Crash-recovery autosave plus clear prompts on close and quit, so an edit is never lost to a mistake.

no clobbering

Safe conflict resolution Pro

If a file changes on disk while you have edits, Twain asks before doing anything: Overwrite, Reload or Cancel. Your work is never silently replaced.

proofing

Spelling that never rewrites

Native spell-check and grammar toggles underline problems; they never auto-correct your Markdown source behind your back.

source editor · snippets

type callout⇥

> [!NOTE] Title
> Body

  ▸ ⇥ moves through the tab stops · your own snippets load from JSON

WYSIWYG where it is safe, source where it matters

In-place editing is a joy on prose and a hazard on components. Twain draws the line explicitly: plain Markdown gets the full rendered-view editing experience, and MDX gets a source editor with live preview, so a stray keystroke can never rewrite a component tree it does not understand.

Built to share files with agents

When something else rewrites a file you are editing, Twain does not guess whose version wins. You choose Overwrite, Reload or Cancel, every time, and local version history keeps what was there before, so even the wrong choice is recoverable.

Try it before buying it

Editing needs Pro, a one-time purchase with a 7-day trial built into the free app. No card details, no sign-up; the trial starts from inside the app.

Questions

Can I edit MDX visually?

No, and that is deliberate. MDX edits happen in the source editor with a live rendered preview beside them. WYSIWYG editing over a component tree is how components get silently broken.

What happens if a file changes on disk while I edit it?

Twain detects the external change and asks: Overwrite, Reload or Cancel. Nothing happens until you choose, and version history records the state before either answer.

Is the editor a subscription?

No. Pro is a one-time purchase. Your licence remains yours, covers every Mac you own, and keeps working with no internet connection.

Can I add my own snippets?

Yes. Drop JSON snippet definitions into Application Support and they join the built-in set, with TextMate-style tab stops in the source editor.

This page describes what the app does today; when a capability is partial or pending, it says so. See how Twain compares to other Mac Markdown apps.

More capabilities

Review and agent loop Export and presentation Workspace and search All capabilities

Try Twain

The free viewer, with a 7-day Pro trial built in.