explaingit

showdownjs/showdown

Analysis updated 2026-06-24 · repo last pushed 2026-01-02

★ 14,854JavaScriptAudience · developerComplexity · 1/5QuietSetup · easy

TLDR

Showdown is a JavaScript Markdown-to-HTML converter that runs in the browser and Node, with many options for GitHub-flavored headers, autolinks, and image dimensions.

Mindmap

mindmap
  root((showdown))
    Inputs
      Markdown strings
      Converter options
      Custom extensions
    Outputs
      HTML strings
      Round-tripped Markdown
    Use Cases
      Render README in browser
      Power a blog engine
      Build a comment system
    Tech Stack
      JavaScript
      Node.js
      Browser
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filefunction / class

What do people build with it?

USE CASE 1

Render Markdown posts to HTML inside a browser page without a build step.

USE CASE 2

Convert Markdown on a Node server before storing the HTML in a database.

USE CASE 3

Power a comment box that accepts Markdown and previews the rendered HTML live.

USE CASE 4

Build a small static site generator that reads .md files and writes HTML pages.

What is it built with?

JavaScriptNode.js

How does it compare?

showdownjs/showdownacdlite/recomposexcanwin/keepchatgpt
Stars14,85414,80914,899
LanguageJavaScriptJavaScriptJavaScript
Last pushed2026-01-02——
MaintenanceQuiet——
Setup difficultyeasyeasyeasy
Complexity1/52/51/5
Audiencedeveloperdevelopergeneral

Figures from each repo's GitHub metadata at analysis time.

How do you get it running?

Difficulty · easy Time to first run · 5min

In plain English

Showdown is a JavaScript library that converts Markdown, the simple text formatting used in things like GitHub README files, into HTML that a browser can render. The project description calls it bidirectional, Markdown to HTML and back, and it traces its lineage back to the original Markdown work by John Gruber. The library is meant to run in two places: in the browser, where you can include it via a script tag from a CDN like jsDelivr, cdnjs, or unpkg, and on a server with Node.js, where you can install it with npm install showdown. Bower and a NuGet package are also offered. The README lists projects that use it or have forked it, including Meteor, Stack Exchange (as a fork called PageDown), and parts of Google Cloud Platform. The quick-start example in the README is short. You require showdown, create a new showdown.Converter, call converter.makeHtml on a Markdown string, and you get HTML back. Both the Node and browser code paths look the same. A large portion of the README is about options. You can set them globally for all converters or locally on a single Converter instance, with setOption, getOption, and getDefaultOptions. The README documents many flags, such as ghCompatibleHeaderId for GitHub-style header anchors, headerLevelStart, parseImgDimensions, and simplifiedAutoLink. The full README is longer than what was shown.

Copy-paste prompts

Prompt 1
Drop Showdown into a single HTML page so a textarea renders live Markdown to HTML on every keystroke.
Prompt 2
Build a Node CLI that reads a folder of Markdown files and writes HTML using Showdown with ghCompatibleHeaderId on.
Prompt 3
Write a small Showdown extension that turns @username tokens into links to a profile page.
Prompt 4
Compare Showdown and marked.js on a 5MB Markdown corpus and report parse time and HTML size.
Prompt 5
Wire Showdown into a React component that previews Markdown with parseImgDimensions and simplifiedAutoLink enabled.

Frequently asked questions

What is showdown?

Showdown is a JavaScript Markdown-to-HTML converter that runs in the browser and Node, with many options for GitHub-flavored headers, autolinks, and image dimensions.

What language is showdown written in?

Mainly JavaScript. The stack also includes JavaScript, Node.js.

Is showdown actively maintained?

Quiet — no commits in 6-12 months (last push 2026-01-02).

How hard is showdown to set up?

Setup difficulty is rated easy, with roughly 5min to a first successful run.

Who is showdown for?

Mainly developer.

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