smep — a Simple Markdown Editor & Previewer, written in Rust

smep is a markdown editor with live preview, built in pure Rust on the GPUI framework (the UI toolkit behind the Zed editor). A frameless window with a small menu bar in its title bar (hide it with a shortcut), and three views: source, split, and a rendered view you edit in place, block by block.

Status

0.1.12 is the thirteenth release: documents open in tabs (a file opened from the file manager, or smep FILE, while smep runs lands in a tab of the open window), an outline of the headings sits beside the document and a click goes to the section, and the document is set the way dfine-blog sets an article (code on a board with a cinnabar tab, a cinnabar top edge on dark paper, tables ruled across) on screen, in the exported page and in the PDF. Before that, 0.1.11 made the stylesheet and the Typst preamble behind the exports yours to edit (smep --css, smep --typst, then export.css / export.typ in the config directory) and showed a document's local images in the preview, on gpui-kit 0.8; and smep got an icon (a cinnabar seal with an M on paper) in the Windows executable, the macOS app and the Linux desktop entry. The Paper look is dfine-blog's (warm white or near-black paper, grey inks, cinnabar), the rendered document is typeset the blog's way in every preview theme, reading mode shows the document as one page (footnotes and selections work across blocks), and the title bar's toggle is Write / Read, no longer a second "Edit". On a Mac, brew install --cask newdee/tap/smep installs smep.app (Finder, Spotlight, the Dock, "Open With", no Terminal window) together with the smep command. Reading mode scrolls from the keyboard and renders .html files as pages, smep notes.md opens a new document when the file is not there yet, and the Windows "Open Markdown Files with smep" no longer flashes a console. It opens reading, and Ctrl+E / Cmd+E or the Write button in the title bar brings the editor. On Windows it opens without a terminal window, and it can make itself the default app for Markdown from the File menu, on top of importing PDF, Word, HTML and text files as Markdown, exporting the document as a PDF or an HTML page, the frameless window with its view modes, in-place editing in the rendered view, opening files from the OS, a Homebrew formula, and typing that stays smooth in large documents. Expect rough edges; the editor and preview are built on gpui-kit and gpui-pre, which are themselves young.

What it does

• Source, split (resizable) or rendered view; the preview updates as you type.
• The rendered view edits in place: click a block and it turns into its Markdown source, sized to its text; click elsewhere or press Escape and it renders again. A click below the last block starts a new one; / there opens the block menu.
• Frameless window: File / Edit / View menus live in the title bar and can be hidden; full screen on a key.
• A menu of blocks (headings, lists, task list, quote, code block, table, divider, image, link) wherever you ask for it: type / on an empty line, click the + beside one, click below the end of the text, or right-click.
• Preview themes (Paper and Paper Dark, GitHub, Newsprint, Night, Sepia, Solarized Light/Dark, or the application's own look): right-click the preview or the rendered document. The choice is remembered in settings.toml under the platform config directory (~/.config/smep, ~/Library/Application Support/smep, %APPDATA%\smep, or $SMEP_CONFIG_DIR).
• Opens reading: the document rendered as one page, nothing to click into by accident, and the keyboard scrolls it (Page Up / Page Down, Space, Home / End, the arrows). The Write button in the title bar (or Ctrl+E) brings the editor in the view mode you last used; Read (or Ctrl+E again) puts it away.
• Markdown highlighting in the editor from the same parser the preview uses.
• The preview follows the editor: whatever block is at the top of the editor is at the top of the preview.
• CommonMark + GFM: tables, task lists, strikethrough, footnotes. Raw HTML inside Markdown renders too, and .html files open straight into the HTML preview.
• Tabs: every document opens in a tab of its own (the bar shows from the second one); Ctrl+T a new one, Ctrl+W closes one, Ctrl+Tab moves on. A file opened from the file manager, or smep FILE while smep is running, lands in a tab of the window that is already open.
• The outline: the document's headings beside it (the Outline button, or Ctrl+Shift+L); a click goes to that section, and the section being read is marked.
• Open, save, save as; an unsaved-changes prompt before a tab or the window closes, for each document with changes.
• Other documents become Markdown: drop a PDF, Word (.docx) or text file on the window, pick one under File, Import as Markdown (HTML too), or pass it on the command line. The result is a new, unsaved document named after the original. PDFs need a text layer; smep does no OCR. Images in Word files are not carried over.
• Export as PDF (typeset by Typst, built in: headings, lists, tables, code, quotes, footnotes, local images; CJK text uses the system's fonts) or as a standalone HTML page, under File. Both wear the preview's look (a PDF the light one of its family: print is ink on paper). smep --css and smep --typst print the stylesheet and the Typst preamble behind them; saved as export.css or export.typ in the config directory, your edited copy is what every export uses.
• Ink on paper: the application wears the Paper look of dfine-blog, light or dark with the system (warm white or near-black paper, grey inks, cinnabar for the cursor, headings and links). The document is set the way the blog sets an article, in every preview theme, on screen, in HTML and in PDF: its heading scale with a fading hairline under h2, code on a board (a whiteboard in a thick aluminium frame on light paper, a thin frame with a cinnabar top edge on dark) with the language in a cinnabar tab and a Copy button, tables ruled across under a heavier header rule. The page and the PDF add what the window cannot draw yet: cinnabar marks before h3 and h4, the quote on a wash under a cinnabar 「, the faded section break, framed images.
• One static binary, no web view, no Electron.

Keys

Install

cargo install smep
smep notes.md

A file that does not exist yet opens as a new document and is written there on the first save. Several files open in tabs, and while smep is running smep FILE hands FILE to that window instead of opening another. On a Mac, Homebrew installs the application:

brew install --cask newdee/tap/smep

The cask puts smep.app in /Applications (Finder, Spotlight, the Dock, "Open With", the default app for .md) and links its binary as the smep command; both follow new releases by themselves. The app is Developer ID signed but not yet notarized, so the first start from Finder is refused once: allow it under System Settings, Privacy & Security, Open Anyway, or install with brew install --cask --no-quarantine newdee/tap/smep.

A bare binary (cargo install, the formula brew install newdee/tap/smep, the release tarball) is a command-line tool to macOS: Finder, Spotlight and "Open With" run it inside a Terminal window, and only an application can claim .md files. Take the cask or the release's smep.app for that. (No Linux formula: that binary needs the system's X11, xkbcommon, Wayland and Vulkan libraries, which a Homebrew prefix does not provide; use cargo install or the release tarball there.) smep --version, smep --help, smep --css [THEME] and smep --typst [THEME] print and exit without opening a window. On Windows smep is a GUI program: no terminal window comes up with it, and in a terminal it still prints. PowerShell neither waits for a GUI program nor captures its output, so a script there asks through cmd /c smep --version (or Start-Process -Wait -RedirectStandardOutput).

Building from source needs a Rust toolchain and, on Linux, a few system libraries; see docs/dev.md. PDF import and PDF export are the two heavy parts of the binary (about 7 MB and 34 MB); a build without them, cargo install smep --no-default-features, keeps everything else and reports the missing feature if asked for it.

Make it the default for .md

File, "Open Markdown Files with smep" does what the system allows:

• macOS: smep claims Markdown files outright, when it runs as smep.app (the Homebrew cask or a GitHub release; a cargo install or formula binary has no bundle, so Finder cannot pick it, and the menu item says so). Files opened from Finder land in the running window. The app is Developer ID signed but not yet notarized, so a downloaded copy goes through Gatekeeper once:
  1. Move smep.app into /Applications (the cask does this).
  2. Open it; when macOS refuses, allow it under System Settings, Privacy & Security, Open Anyway (older systems: right-click, Open). That is a one-time pass for this copy of the app.
  3. Pick File, "Open Markdown Files with smep", or in Finder select a .md file, Get Info, Open With, smep, Change All. The association is kept by bundle id and survives updates; each newly downloaded version needs step 2 again until the app is notarized (brew install --cask --no-quarantine skips it).
• Windows: smep registers itself (current user, no admin) and opens the Settings page for it, where you choose smep next to .md once; Windows keeps that choice to itself. scripts\register-windows.ps1 does the same registration from a terminal.
• Linux: smep writes ~/.local/share/applications/smep.desktop (and its icon into ~/.local/share/icons) and runs xdg-mime default smep.desktop text/markdown. (assets/smep.desktop and the smep.png in the release tarball are the same files, for doing it by hand.)

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT license (LICENSE-MIT)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this work by you shall be dual licensed as above, without any additional terms or conditions.