Building Extensions

An extension adds something to Typora: a code-block language that draws a diagram, a view in the detail panel, a viewer for a file type, TeX macros, templates, commands, and more. One extension package runs unchanged on macOS, Windows and Linux.

Most extensions need no code at all. A JSON manifest is enough to add Kroki diagrams, issue links, task lists, input rules or snippets. When you need custom rendering you add an HTML page; when you need logic you add a script that runs in a Worker.

Trust tiers

Everything an extension contributes belongs to one of three tiers. The tier decides where it runs and what it can reach.

Tier	What it is	Runs in	Can reach
L0 — data	JSON in the manifest, Markdown templates and snippets, TeX macros	Interpreted by Typora	Nothing — Typora applies it
L1 — pages	HTML / JS / WASM pages: fence renderers, detail views, file viewers	A sandboxed frame with its own origin	Only the messages Typora sends it, and the View SDK
L2 — logic	A main script (one per window) and/or a background script (one per app)	A locked-down Worker per extension	Only the Worker API, filtered by permissions

Rules that hold for every tier:

1. A Markdown document is data. Fence bodies, inline text and front matter are passed to your extension as input. Opening a file never runs code.
2. No extension code runs inside the editor. Pages run in sandboxed frames, scripts run in Workers. Neither can touch the editor's DOM or internal state.
3. No network, storage or file access by default. Pages and Workers have connect-src 'none'. Network, storage and clipboard go through Typora and are limited to what the user granted.
4. Everything is disposable. All contributions are removed when an extension is disabled, uninstalled or reloaded.

There is no "full trust" mode: no shell commands, no arbitrary file system access, no Node.js.

What a package looks like

An extension is a folder named after its id, with a typora-extension.json manifest at the top:

yourname.hello/
  typora-extension.json     manifest (required)
  main.js                   L2 script, optional
  renderer.html             L1 page, optional
  snippets/                 L0 files, optional

Installed extensions live in ~/.config/Typora/Extensions/<id>/ (inside the app's container in sandboxed macOS builds). Users install them from the store, from a folder or a .typora-extension file in Settings ▸ Extensions.

Where to go next

• Quick Start — write, install and reload a first extension.
• Manifest Reference — every field of typora-extension.json.
• Contribution Points — what you can add, with examples.
• View SDK and Worker API — the APIs for pages and scripts.
• Permissions and Security — what to declare and what users see.
• Publishing — get your extension into the store.
• Samples — fifteen complete extensions to copy from.