# Show HN: Slidown – Markdown to PowerPoint in pure Go, no AI in generation > Source: > Published: 2026-07-07 04:54:56+00:00 `slidown` is a tool for creating PowerPoint (`.pptx` ) presentations from Markdown. It is a sibling project of [ k1LoW/deck](https://github.com/k1LoW/deck), a Markdown → Google Slides tool by [@k1LoW](https://github.com/k1LoW). `slidown` shares `deck` 's philosophy of *Markdown for content, slide tooling for design*, and adopts the same Markdown format and element mapping. The difference is the output target: `slidown` writes standalone `.pptx` files via a pure-Go OOXML writer, with no third-party Office dependencies.`deck` and `slidown` are designed to be used together or interchangeably from the same Markdown source, so you can pick the right delivery target — Google Slides or PowerPoint — without rewriting your slides. **Homebrew:** ``` bash $ brew install Songmu/tap/slidown ``` **go install:** ``` bash $ go install github.com/Songmu/slidown/cmd/slidown@latest ``` Write your slides in Markdown: ``` --- title: Talk about slidown --- # First slide ## A subtitle - a bullet point - **bold** and *italic* and `code` - a nested point --- # Second slide A paragraph with a [link](https://example.com). ``` Then apply it to a `.pptx` : ``` bash $ slidown apply deck.md Wrote deck.pptx (2 slide(s)) ``` By default the output file is the input file name with a `.pptx` extension. Override it with `--output` /`-o` , or with the `output` frontmatter field: ``` bash $ slidown apply deck.md -o talk.pptx ``` If the output `.pptx` already exists, `apply` updates it in place. Slides whose source content has not changed keep their existing slide parts verbatim, so manual edits made in PowerPoint to unchanged slides are preserved; only changed slides are regenerated: ``` bash $ slidown apply deck.md -o deck.pptx Updated deck.pptx (2 slide(s)) ``` Image-only differences (recompression, reordering or repositioning) are treated as unchanged, so adjusting images in PowerPoint does not trigger a regenerate. To make reuse robust against page reordering, give a page a stable `key` — otherwise pages are matched by position: ``` php # Overview ``` A page can also be **frozen** with the `freeze` page configuration. A frozen page keeps its existing slide as-is on rebuild even if its Markdown changed — useful for pinning a slide you have hand-tuned in PowerPoint: ``` php # Hand-tuned slide ``` To bring in a slide **pasted from another presentation**, declare a keyed, frozen placeholder page for it in the Markdown and paste the slide at that position in PowerPoint: ``` php # Imported slide ``` On rebuild, `apply` pairs the placeholder with the pasted slide by position, keeps the pasted slide verbatim (`freeze` ), and stamps the `key` onto it — so later rebuilds match it by key even after reordering. The deck source is authoritative for keys: a key renamed or removed in the Markdown is updated or cleared on the slide accordingly, and `freeze: true` need only stay in the Markdown. Use `--watch` (or `-w` ) to keep `apply` running and automatically re-apply when the deck markdown file changes: ``` bash $ slidown apply deck.md --watch Wrote deck.pptx (2 slide(s)) Updated deck.pptx (2 slide(s)) ``` `slidown` watches the deck file's directory so editor atomic-save patterns (`rename` /`remove` + `create` ) are handled, filters events to the deck file, and debounces bursts so one save triggers one rebuild. If a rebuild fails, the error is printed and watch mode keeps running until you stop it with `Ctrl-C` . `--watch` and `--template` are mutually exclusive. `--template` is only for initial generation; when you need watch mode with a template, set `template` in the config file instead. MVP scope: watch mode currently tracks deck markdown file changes only. Supply a `.pptx` (or `.potx` ) whose theme, slide masters and layouts should be used as the design when creating a new output file: ``` bash $ slidown apply deck.md --template theme.pptx ``` A template can only be supplied when the output file does not yet exist. It may also be set with the `template` config field. When the output already exists it is updated in place, reusing itself as the template, and passing `--template` is an error (choose a different `--output` , or remove the file first). See [docs/templates.md](/Songmu/slidown/blob/main/docs/templates.md) for layout selection, inspecting available layouts with `ls-layouts` , and repurposing existing placeholders as subtitle targets. Templates can also include a [ style layout](/Songmu/slidown/blob/main/docs/templates.md#style-layout) to customize inline syntax and table styling. Incremental updates reuse unchanged slides from the existing output file and still honor `freeze: true` .The Markdown used by `slidown` consists of an optional YAML frontmatter and a body. Slides are separated by a line of three or more hyphens (`---` ). ``` --- title: Talk about slidown output: talk.pptx --- # First Slide Content... ``` `title` (string): The title of the presentation, written to the generated`.pptx` document properties (metadata).`output` (string): Output`.pptx` path (used when`--output` is not given).`breaks` (boolean): Control how single line breaks are rendered. Default (`false` ) renders them as spaces;`true` preserves them as line breaks.`codeBlockToImageCommand` (string): Command used to convert code blocks to images (see[Code blocks to images](#code-blocks-to-images)).`defaults` (array): Conditional page configuration using CEL expressions. `slidown` follows the same Markdown specification as `deck` : CommonMark plus selected GitHub Flavored Markdown extensions (tables, strikethrough), with a restricted set of raw inline HTML for text-level semantics (`` , `` , `` , `` , `` , …). Speaker notes are written as HTML comments (`` ). Within each slide, headings are mapped to placeholders by depth: - The **shallowest** heading on the slide →**title** - The **next** heading level →**subtitle** - Everything else → **body** See [docs/markdown.md](/Songmu/slidown/blob/main/docs/markdown.md) for the full Markdown reference, including supported/unsupported features, inline-style mappings and line-break handling. A few edge behaviors (notably how content that overflows the available placeholders is handled) currently differ from `deck` and are not yet a stable contract; these are called out inline in that reference. `slidown` reads optional global configuration: `${XDG_CONFIG_HOME:-~/.config}/slidown/config-{profile}.yml` (with`--profile` )`${XDG_CONFIG_HOME:-~/.config}/slidown/config.yml` ``` breaks: true codeBlockToImageCommand: "go run ./cmd/txt2img" template: "theme.pptx" ``` Settings in frontmatter take precedence over the configuration file. The `template` field is honored only from the configuration file (or the `--template` flag) and only when creating a new output file; it cannot be set in a deck's frontmatter. You can convert Markdown code blocks to images by specifying a command that outputs image data (PNG/JPEG/GIF) to standard output, or to a file via the `{{output}}` placeholder: ``` bash $ slidown apply deck.md --code-block-to-image-command "some-command" ``` This is useful for rendering diagrams (e.g. Mermaid) or syntax-highlighted code as images. `slidown` is under active development. `apply` already reuses unchanged whole slides; finer-grained intra-slide (sub-element) diffing is future work. See [docs/design.md](/Songmu/slidown/blob/main/docs/design.md) for the architecture and the incremental-rebuild design. —`k1LoW/deck` `slidown` is a sibling project of`deck` and reuses its Markdown parsing and content model. The Markdown specification, the element-to-slide mapping rules and much of the surrounding design come from`deck` . Many thanks to[@k1LoW](https://github.com/k1LoW)and the`deck` contributors.