# Markdown Flavor Compatibility Matrix Which Markdown features work on which platforms — 21 features × 8 platforms, every cell verified against official documentation. - Source page: https://www.markdowntools.io/cheat-sheet - Dataset version: 2026-07-18 (last verification pass) - Machine-readable: [CSV](https://www.markdowntools.io/downloads/markdown-flavor-compatibility.csv) · [JSON](https://www.markdowntools.io/downloads/markdown-flavor-compatibility.json) - Report a correction: https://github.com/waydelyle/markdowntools/issues/new Legend: ✅ yes · ⚠️ partial · ❌ no | Feature | Syntax | CommonMark | GitHub | GitLab | Obsidian | Discord | Slack | Reddit | Jupyter / Rmd | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | Headings | `# Heading 1` | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ⚠️ partial | ❌ no | ✅ yes | ✅ yes | | Bold | `**bold text**` | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | | Italic | `*italic text*` | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | | Strikethrough | `~~struck text~~` | ❌ no | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ⚠️ partial | | Underline | `text (HTML)` | ❌ no | ⚠️ partial | ❌ no | ⚠️ partial | ✅ yes | ⚠️ partial | ❌ no | ⚠️ partial | | Tables | `\| A \| B \|
\| --- \| --- \|` | ❌ no | ✅ yes | ✅ yes | ✅ yes | ❌ no | ❌ no | ✅ yes | ✅ yes | | Task lists | `- [x] done
- [ ] todo` | ❌ no | ✅ yes | ✅ yes | ✅ yes | ❌ no | ❌ no | ❌ no | ⚠️ partial | | Footnotes | `Text.[^1]

[^1]: The note.` | ❌ no | ✅ yes | ✅ yes | ✅ yes | ❌ no | ❌ no | ❌ no | ⚠️ partial | | Math (LaTeX) | `$x^2$` | ❌ no | ✅ yes | ✅ yes | ✅ yes | ❌ no | ❌ no | ❌ no | ✅ yes | | Mermaid / diagrams | `` ```mermaid
graph TD
A --> B
``` `` | ❌ no | ✅ yes | ✅ yes | ✅ yes | ❌ no | ❌ no | ❌ no | ⚠️ partial | | Raw HTML | `
text
` | ✅ yes | ⚠️ partial | ⚠️ partial | ⚠️ partial | ❌ no | ❌ no | ❌ no | ⚠️ partial | | Spoilers | `\|\|hidden text\|\|` | ❌ no | ⚠️ partial | ⚠️ partial | ❌ no | ✅ yes | ❌ no | ✅ yes | ❌ no | | Dynamic timestamps | `` | ❌ no | ❌ no | ❌ no | ❌ no | ✅ yes | ⚠️ partial | ❌ no | ❌ no | | Callouts / alerts | `> [!note]
> Content` | ❌ no | ✅ yes | ✅ yes | ✅ yes | ❌ no | ❌ no | ❌ no | ❌ no | | Wikilinks | `[[Page Name]]` | ❌ no | ⚠️ partial | ⚠️ partial | ✅ yes | ❌ no | ❌ no | ❌ no | ❌ no | | Highlight | `==highlighted text==` | ❌ no | ❌ no | ❌ no | ✅ yes | ❌ no | ❌ no | ❌ no | ❌ no | | Comments (hidden text) | `%%hidden%%` | ⚠️ partial | ✅ yes | ⚠️ partial | ✅ yes | ❌ no | ❌ no | ❌ no | ⚠️ partial | | Code blocks | `` ```js
code
``` `` | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ⚠️ partial | ✅ yes | | Blockquotes | `> quoted text` | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | | Images | `![alt text](image.jpg)` | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ❌ no | ❌ no | ⚠️ partial | ✅ yes | | Links | `[text](https://example.com)` | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ✅ yes | ⚠️ partial | ✅ yes | ✅ yes | ## Platform sources - **CommonMark** — https://spec.commonmark.org/0.31.2/ (verified 2026-07-18) - **GitHub Flavored Markdown** — https://github.github.com/gfm/ (verified 2026-07-18) - **GitLab Flavored Markdown** — https://docs.gitlab.com/user/markdown/ (verified 2026-07-18) - **Obsidian** — https://help.obsidian.md/syntax (verified 2026-07-18) - **Discord** — https://support.discord.com/hc/en-us/articles/210298617-Markdown-Text-101-Chat-Formatting-Bold-Italic-Underline (verified 2026-07-18) - **Slack** — https://slack.com/help/articles/202288908-Format-your-messages (verified 2026-07-18) - **Reddit** — https://support.reddithelp.com/hc/en-us/articles/360043033952-Formatting-Guide (verified 2026-07-18) - **Jupyter / R Markdown** — https://jupyter-notebook.readthedocs.io/en/stable/examples/Notebook/Working%20With%20Markdown%20Cells.html (verified 2026-07-18) ## Notes by feature ### Headings Source: https://spec.commonmark.org/0.31.2/#atx-headings - **CommonMark** — ✅ yes: ATX (#) and Setext styles; levels 1–6. - **GitHub Flavored Markdown** — ✅ yes: Levels 1–6 with auto-generated anchors. - **GitLab Flavored Markdown** — ✅ yes: Levels 1–6, Setext alternative; auto anchors. - **Obsidian** — ✅ yes: Levels 1–6; appear in the outline pane. - **Discord** — ⚠️ partial: H1–H3 (# to ###) plus -# subtext only. - **Slack** — ❌ no: Not in message formatting; canvases only. - **Reddit** — ✅ yes: Six levels; Setext underline style also works. - **Jupyter / R Markdown** — ✅ yes: Supported in Jupyter cells and R Markdown. ### Bold Source: https://spec.commonmark.org/0.31.2/#emphasis-and-strong-emphasis - **CommonMark** — ✅ yes: ** or __ delimiters. - **GitHub Flavored Markdown** — ✅ yes: ** or __. - **GitLab Flavored Markdown** — ✅ yes: ** or __. - **Obsidian** — ✅ yes: ** or __. - **Discord** — ✅ yes: **text** only; __ is underline here. - **Slack** — ✅ yes: *text* markup or the toolbar button. - **Reddit** — ✅ yes: ** or __. - **Jupyter / R Markdown** — ✅ yes: ** or __ in both. ### Italic Source: https://spec.commonmark.org/0.31.2/#emphasis-and-strong-emphasis - **CommonMark** — ✅ yes: * or _ delimiters. - **GitHub Flavored Markdown** — ✅ yes: * or _. - **GitLab Flavored Markdown** — ✅ yes: * or _; intra-word underscores ignored. - **Obsidian** — ✅ yes: * or _. - **Discord** — ✅ yes: *text* or _text_. - **Slack** — ✅ yes: _text_ markup or the toolbar button. - **Reddit** — ✅ yes: * or _. - **Jupyter / R Markdown** — ✅ yes: * or _ in both. ### Strikethrough Source: https://github.github.com/gfm/#strikethrough-extension- - **CommonMark** — ❌ no: Not in the spec. - **GitHub Flavored Markdown** — ✅ yes: GFM extension; GitHub also accepts a single ~. - **GitLab Flavored Markdown** — ✅ yes: GLFM: ~~double tildes~~. - **Obsidian** — ✅ yes: GFM-style ~~text~~. - **Discord** — ✅ yes: ~~text~~. - **Slack** — ✅ yes: ~text~ (single tilde) or the toolbar. - **Reddit** — ✅ yes: ~~double tildes~~. - **Jupyter / R Markdown** — ⚠️ partial: R Markdown (Pandoc strikeout): yes; not documented for Jupyter cells. ### Underline Source: https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax - **CommonMark** — ❌ no: No syntax; raw / HTML is the only option. - **GitHub Flavored Markdown** — ⚠️ partial: No Markdown syntax; GitHub documents the tag. - **GitLab Flavored Markdown** — ❌ no: No documented underline syntax. - **Obsidian** — ⚠️ partial: HTML works; no Markdown syntax, and Markdown inside HTML is not processed. - **Discord** — ✅ yes: __text__ (Discord extension). - **Slack** — ⚠️ partial: Toolbar only; no markup shortcut. - **Reddit** — ❌ no: Not supported. - **Jupyter / R Markdown** — ⚠️ partial: No Markdown syntax; raw passes through to HTML output. ### Tables Source: https://github.github.com/gfm/#tables-extension- - **CommonMark** — ❌ no: Not in the spec. - **GitHub Flavored Markdown** — ✅ yes: GFM tables extension with column alignment. - **GitLab Flavored Markdown** — ✅ yes: GLFM tables; paste from spreadsheets works. - **Obsidian** — ✅ yes: Plus Live Preview table editing. - **Discord** — ❌ no: No table syntax. - **Slack** — ❌ no: No tables in messages. - **Reddit** — ✅ yes: Pipe tables; parsing quirks differ between old and new Reddit. - **Jupyter / R Markdown** — ✅ yes: Jupyter renders GFM tables; R Markdown supports pipe tables. ### Task lists Source: https://github.github.com/gfm/#task-list-items-extension- - **CommonMark** — ❌ no: Not in the spec. - **GitHub Flavored Markdown** — ✅ yes: GFM task list extension. - **GitLab Flavored Markdown** — ✅ yes: Adds an inapplicable [~] state. - **Obsidian** — ✅ yes: Any character inside the brackets marks a task complete. - **Discord** — ❌ no: Renders as a plain list item. - **Slack** — ❌ no: No Markdown syntax for tasks. - **Reddit** — ❌ no: Renders as a plain list item. - **Jupyter / R Markdown** — ⚠️ partial: R Markdown (Pandoc task_lists): yes; not documented for Jupyter cells. ### Footnotes Source: https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax#footnotes - **CommonMark** — ❌ no: Not in the spec. - **GitHub Flavored Markdown** — ✅ yes: GitHub.com extension; not part of the GFM spec itself. - **GitLab Flavored Markdown** — ✅ yes: GLFM footnotes. - **Obsidian** — ✅ yes: Plus inline ^[...] footnotes. - **Discord** — ❌ no: Renders as literal [^1]. - **Slack** — ❌ no: Not supported. - **Reddit** — ❌ no: Renders as literal [^1]. - **Jupyter / R Markdown** — ⚠️ partial: R Markdown (Pandoc footnotes): yes; Jupyter cells do not render them. ### Math (LaTeX) Source: https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/writing-mathematical-expressions - **CommonMark** — ❌ no: Not in the spec. - **GitHub Flavored Markdown** — ✅ yes: MathJax on github.com; $ inline and $$ blocks. - **GitLab Flavored Markdown** — ✅ yes: KaTeX; $`...`$ inline and ```math blocks. - **Obsidian** — ✅ yes: MathJax; $ inline and $$ blocks. - **Discord** — ❌ no: Not supported. - **Slack** — ❌ no: Not supported. - **Reddit** — ❌ no: No native rendering. - **Jupyter / R Markdown** — ✅ yes: MathJax in Jupyter cells; LaTeX math in R Markdown. ### Mermaid / diagrams Source: https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/creating-diagrams - **CommonMark** — ❌ no: Renders as a plain code block. - **GitHub Flavored Markdown** — ✅ yes: Mermaid blocks render as diagrams on github.com. - **GitLab Flavored Markdown** — ✅ yes: ```mermaid; PlantUML and Kroki also available. - **Obsidian** — ✅ yes: Native Mermaid rendering in notes. - **Discord** — ❌ no: Renders as a code block. - **Slack** — ❌ no: Renders as a code block. - **Reddit** — ❌ no: Renders as a code block. - **Jupyter / R Markdown** — ⚠️ partial: JupyterLab 4.1+ renders ```mermaid natively; R Markdown needs the DiagrammeR package. ### Raw HTML Source: https://spec.commonmark.org/0.31.2/#raw-html - **CommonMark** — ✅ yes: HTML blocks and inline HTML are part of the spec. - **GitHub Flavored Markdown** — ⚠️ partial: Sanitized subset; scripts and some tags are stripped. - **GitLab Flavored Markdown** — ⚠️ partial: Sanitized subset (e.g.
and
). - **Obsidian** — ⚠️ partial: Renders HTML, but Markdown inside HTML is intentionally not processed. - **Discord** — ❌ no: HTML renders as literal text. - **Slack** — ❌ no: No HTML rendering. - **Reddit** — ❌ no: Tags render as literal text; only HTML entities work. - **Jupyter / R Markdown** — ⚠️ partial: Jupyter renders raw HTML; R Markdown passes it to HTML output only. ### Spoilers Source: https://support.discord.com/hc/en-us/articles/210298617-Markdown-Text-101-Chat-Formatting-Bold-Italic-Underline - **CommonMark** — ❌ no: Not in the spec. - **GitHub Flavored Markdown** — ⚠️ partial: No spoiler syntax;
HTML gives collapsible sections. - **GitLab Flavored Markdown** — ⚠️ partial: No spoiler syntax;
/ HTML. - **Obsidian** — ❌ no: No spoiler syntax. - **Discord** — ✅ yes: ||text|| hides content until clicked. - **Slack** — ❌ no: Not supported. - **Reddit** — ✅ yes: >!text!< syntax — different delimiters from Discord. - **Jupyter / R Markdown** — ❌ no: Not supported. ### Dynamic timestamps Source: https://support.discord.com/hc/en-us/articles/210298617-Markdown-Text-101-Chat-Formatting-Bold-Italic-Underline - **CommonMark** — ❌ no: Not in the spec. - **GitHub Flavored Markdown** — ❌ no: Not supported. - **GitLab Flavored Markdown** — ❌ no: Not supported. - **Obsidian** — ❌ no: Not supported. - **Discord** — ✅ yes: renders in each viewer’s timezone; seven formats. - **Slack** — ⚠️ partial: Via in app/bot messages (Slack mrkdwn). - **Reddit** — ❌ no: Not supported. - **Jupyter / R Markdown** — ❌ no: Not supported. ### Callouts / alerts Source: https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax#alerts - **CommonMark** — ❌ no: Renders as a plain blockquote. - **GitHub Flavored Markdown** — ✅ yes: Alerts: NOTE, TIP, IMPORTANT, WARNING, CAUTION. - **GitLab Flavored Markdown** — ✅ yes: GLFM alerts (note, tip, warning, caution, important). - **Obsidian** — ✅ yes: 13 types with aliases, folding, and nesting. - **Discord** — ❌ no: Renders as a plain blockquote. - **Slack** — ❌ no: Renders as a plain quote. - **Reddit** — ❌ no: Renders as a plain blockquote. - **Jupyter / R Markdown** — ❌ no: Quarto (R Markdown’s successor) adds callout blocks; classic R Markdown has none. ### Wikilinks Source: https://help.obsidian.md/links - **CommonMark** — ❌ no: Not in the spec. - **GitHub Flavored Markdown** — ⚠️ partial: [[links]] resolve in GitHub wiki pages only. - **GitLab Flavored Markdown** — ⚠️ partial: [[Page]] works in wiki pages; regular files and comments do not resolve it. - **Obsidian** — ✅ yes: Vault-native; auto-updates when the target note is renamed. - **Discord** — ❌ no: Renders as literal brackets. - **Slack** — ❌ no: Not supported. - **Reddit** — ❌ no: Renders as literal brackets. - **Jupyter / R Markdown** — ❌ no: Renders as literal brackets. ### Highlight Source: https://help.obsidian.md/syntax - **CommonMark** — ❌ no: Not in the spec. - **GitHub Flavored Markdown** — ❌ no: Renders as literal ==. - **GitLab Flavored Markdown** — ❌ no: Renders as literal ==. - **Obsidian** — ✅ yes: ==text== marker-style highlight. - **Discord** — ❌ no: Renders as literal ==. - **Slack** — ❌ no: Not supported. - **Reddit** — ❌ no: Renders as literal ==. - **Jupyter / R Markdown** — ❌ no: Pandoc’s ==mark== extension exists but is off by default. ### Comments (hidden text) Source: https://help.obsidian.md/syntax#Comments - **CommonMark** — ⚠️ partial: Via HTML comments; hidden but kept in the output source. - **GitHub Flavored Markdown** — ✅ yes: GitHub documents hiding content with comments. - **GitLab Flavored Markdown** — ⚠️ partial: No dedicated syntax; HTML comments. - **Obsidian** — ✅ yes: %%comment%% hides text in Reading view and on publish. - **Discord** — ❌ no: Not supported. - **Slack** — ❌ no: Not supported. - **Reddit** — ❌ no: Not supported. - **Jupyter / R Markdown** — ⚠️ partial: hidden in HTML output only. ### Code blocks Source: https://spec.commonmark.org/0.31.2/#fenced-code-blocks - **CommonMark** — ✅ yes: Fenced and indented blocks. - **GitHub Flavored Markdown** — ✅ yes: Fenced, with syntax highlighting. - **GitLab Flavored Markdown** — ✅ yes: Fenced; 100+ highlight languages. - **Obsidian** — ✅ yes: Fenced, with syntax highlighting. - **Discord** — ✅ yes: ``` with optional language. - **Slack** — ✅ yes: ``` or the toolbar code block. - **Reddit** — ⚠️ partial: Fenced blocks only on new Reddit; old Reddit supports indented blocks only. - **Jupyter / R Markdown** — ✅ yes: Fenced blocks; R Markdown chunks also execute code. ### Blockquotes Source: https://spec.commonmark.org/0.31.2/#block-quotes - **CommonMark** — ✅ yes: > at the start of a line. - **GitHub Flavored Markdown** — ✅ yes: > at the start of a line. - **GitLab Flavored Markdown** — ✅ yes: > at the start of a line. - **Obsidian** — ✅ yes: > at the start of a line. - **Discord** — ✅ yes: > for one line; >>> quotes the rest of the message. - **Slack** — ✅ yes: > markup or the toolbar. - **Reddit** — ✅ yes: > at the start of a line. - **Jupyter / R Markdown** — ✅ yes: > at the start of a line. ### Images Source: https://spec.commonmark.org/0.31.2/#images - **CommonMark** — ✅ yes: ![alt](url) with optional title. - **GitHub Flavored Markdown** — ✅ yes: ![alt](url); relative paths and uploads supported. - **GitLab Flavored Markdown** — ✅ yes: ![alt](url); uploads supported. - **Obsidian** — ✅ yes: Plus ![[embeds]] for vault files. - **Discord** — ❌ no: Attachments/embeds only; no Markdown image syntax. - **Slack** — ❌ no: File uploads only; no Markdown image syntax. - **Reddit** — ⚠️ partial: No Markdown image syntax; the rich-text editor supports image uploads. - **Jupyter / R Markdown** — ✅ yes: Standard syntax; Jupyter also supports attachment: references. ### Links Source: https://spec.commonmark.org/0.31.2/#links - **CommonMark** — ✅ yes: Inline, reference, and autolinks. - **GitHub Flavored Markdown** — ✅ yes: Inline, reference, and autolinks. - **GitLab Flavored Markdown** — ✅ yes: Inline, reference, and autolinks. - **Obsidian** — ✅ yes: Inline links; [[wikilinks]] are the default. - **Discord** — ✅ yes: Masked links [text](url) in user messages. - **Slack** — ⚠️ partial: Composer toolbar or paste-to-link; mrkdwn uses . - **Reddit** — ✅ yes: Inline, reference, and autolinks. - **Jupyter / R Markdown** — ✅ yes: Inline links in both.