html-to-markdown

A robust html-to-markdown converter that transforms HTML (even entire websites) into clean, readable Markdown. It supports complex formatting, customizable options, and plugins for full control over the conversion process.

Use the fully extendable Golang library or a quick CLI command. Alternatively, try the Online Demo or REST API to see it in action!

Here are some cool features:

• Bold & Italic: Supports bold and italic—even within single words.

  

• List: Handles ordered and unordered lists with full nesting support.

  

• Blockquote: Blockquotes can include other elements, with seamless support for nested quotes.

  

• Inline Code & Code Block: Correctly handles backticks and multi-line code blocks, preserving code structure.

  

• Link & Image: Properly formats multi-line links, adding escapes for blank lines where needed.

  

• Smart Escaping: Escapes special characters only when necessary, to avoid accidental Markdown rendering. 🗒️ ESCAPING.md

  

• Remove/Keep HTML: Choose to strip or retain specific HTML tags for ultimate control over output.

  

• Plugins: Easily extend with plugins. Or create custom ones to enhance functionality.

  

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Golang Library

Installation

go get -u github.com/JohannesKaufmann/html-to-markdown/v2

Or if you want a specific commit add the suffix /v2@commithash

Note

This is the documentation for the v2 library. For the old version switch to the "v1" branch.

Usage

package main

import (
	"fmt"
	"log"

	htmltomarkdown "github.com/JohannesKaufmann/html-to-markdown/v2"
)

func main() {
	input := `<strong>Bold Text</strong>`

	markdown, err := htmltomarkdown.ConvertString(input)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(markdown)
	// Output: **Bold Text**
}

• 🧑‍💻 Example code, basics

Use WithDomain to convert relative links to absolute links:

package main

import (
	"fmt"
	"log"

	htmltomarkdown "github.com/JohannesKaufmann/html-to-markdown/v2"
	"github.com/JohannesKaufmann/html-to-markdown/v2/converter"
)

func main() {
	input := `<img src="/assets/image.png" />`

	markdown, err := htmltomarkdown.ConvertString(
		input,
		converter.WithDomain("https://example.com"),
	)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(markdown)
	// Output: ![](https://example.com/assets/image.png)
}

The function htmltomarkdown.ConvertString() is a small wrapper around converter.NewConverter() and the base and commonmark plugins. If you want more control, use the following:

package main

import (
	"fmt"
	"log"

	"github.com/JohannesKaufmann/html-to-markdown/v2/converter"
	"github.com/JohannesKaufmann/html-to-markdown/v2/plugin/base"
	"github.com/JohannesKaufmann/html-to-markdown/v2/plugin/commonmark"
)

func main() {
	input := `<strong>Bold Text</strong>`

	conv := converter.NewConverter(
		converter.WithPlugins(
			base.NewBasePlugin(),
			commonmark.NewCommonmarkPlugin(
				commonmark.WithStrongDelimiter("__"),
				// ...additional configurations for the plugin
			),
		),
	)

	markdown, err := conv.ConvertString(input)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(markdown)
	// Output: __Bold Text__
}

• 🧑‍💻 Example code, options

Note

If you use NewConverter directly make sure to also register the commonmark and base plugin.

Plugins

Published Plugins

These are the plugins located in the plugin folder:

Name	Description
Base	Implements basic shared functionality (e.g. removing nodes)
Commonmark	Implements Markdown according to the Commonmark Spec
GitHubFlavored	planned
TaskListItems	planned
Strikethrough	Converts <strike>, <s>, and <del> to the ~~ syntax.
Table	planned
VimeoEmbed	planned
YoutubeEmbed	planned
ConfluenceCodeBlock	planned
ConfluenceAttachments	planned

Note

Not all the plugins from v1 are already ported to v2. These will soon be implemented...

These are the plugins in other repositories:

Name	Description
[Plugin Name](Your Link)	A short description

Writing Plugins

You want to write custom logic?

1. Write your logic and register it.

   

   • 🧑‍💻 Example code, register

2. Optional: Package your logic into a plugin and publish it.

   • 🗒️ WRITING_PLUGINS.md

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CLI - Using it on the command line

Using the Golang library provides the most customization, while the CLI is the simplest way to get started.

Installation

Homebrew Tap

brew install JohannesKaufmann/tap/html2markdown

Manually

Download the pre-compiled binaries from the releases page and copy them to the desired location.

Version

html2markdown --version

Note

Make sure that --version prints 2.X.X as there is a different CLI for V2 of the converter.

Usage

$ echo "<strong>important</strong>" | html2markdown

**important**

$ curl --no-progress-meter http://example.com | html2markdown

# Example Domain

This domain is for use in illustrative examples in documents. You may use this domain in literature without prior coordination or asking for permission.

[More information...](https://www.iana.org/domains/example)

Use --help to learn about the configurations, for example:

• --domain="https://example.com" to convert relative links to absolute links.
• --exclude-selector=".ad" to exclude the html elements with class="ad" from the conversion.
• --include-selector="article" to only include the <article> html elements in the conversion.

(The cli does not support every option yet. Over time more customization will be added)

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FAQ

Extending with Plugins

• Need your own logic? Write your own code and then register it.

  • Don't like the defaults that the library uses? You can use PriorityEarly to run you logic earlier than others.

  • 🧑‍💻 Example code, register

• If you believe that you logic could also benefit others, you can package it up into a plugin.

  • 🗒️ WRITING_PLUGINS.md

Bugs

You found a bug?

Open an issue with the HTML snippet that does not produce the expected results. Please, please, plase submit the HTML snippet that caused the problem. Otherwise it is very difficult to reproduce and fix...

Security

This library produces markdown that is readable and can be changed by humans.

Once you convert this markdown back to HTML (e.g. using goldmark or blackfriday) you need to be careful of malicious content.

This library does NOT sanitize untrusted content. Use an HTML sanitizer such as bluemonday before displaying the HTML in the browser.

🗒️ SECURITY.md if you find a security vulnerability

Goroutines

You can use the Converter from (multiple) goroutines. Internally a mutex is used & there is a test to verify that behaviour.

Escaping & Backslash

Some characters have a special meaning in markdown (e.g. "*" for emphasis). The backslash \ character is used to "escape" those characters. That is perfectly safe and won't be displayed in the final render.

🗒️ ESCAPING.md

Contributing

You want to contribute? Thats great to hear! There are many ways to help:

Helping to answer questions, triaging issues, writing documentation, writing code, ...

If you want to make a code change: Please first discuss the change you wish to make, by opening an issue. I'm also happy to guide you to where a change is most likely needed. There are also extensive tests (see below) so you can freely experiment 🧑‍🔬

Note: The outside API should not change because of backwards compatibility...

Testing

You don't have to be afraid of breaking the converter, since there are many "Golden File" tests:

Add your problematic HTML snippet to one of the .in.html files in the testdata folders. Then run go test -update and have a look at which .out.md files changed in GIT.

You can now change the internal logic and inspect what impact your change has by running go test -update again.

Note: Before submitting your change as a PR, make sure that you run those tests and check the files into GIT...

License

Unless otherwise specified, the project is licensed under the terms of the MIT license.

🗒️ LICENSE