Working with Markdown in Go: libraries blackfriday, goldmark and chroma

Working with Markdown in Go (Golang): an overview of popular libraries

Go (Golang) is a modern compiled language often chosen for creating high-performance web applications, CLI utilities, and tools for generating static sites. One typical task is processing Markdown markup. In this article, we will look at three key libraries: blackfriday, goldmark and chroma, and also show how to combine them to create a full-featured Markdown to HTML converter with syntax highlighting.

1. Why process Markdown in Go?

Markdown is a lightweight markup language widely used in documentation, blogs, README files, and content management systems. In the Go ecosystem, there are several mature libraries that allow you to:

• Convert Markdown to HTML for web publishing.
• Add syntax highlighting for code blocks.
• Create custom extensions (e.g., support for LaTeX, diagrams, or custom blocks).
• Integrate with static site generators (Hugo, custom solutions).

2. The blackfriday library (v2)

Blackfriday is one of the oldest and most popular libraries for Go. It is known for its high speed and behavior close to the CommonMark standard. Installation:

go get github.com/russross/blackfriday/v2

A simple usage example:

package main

import (    "fmt"    "github.com/russross/blackfriday/v2")

func main() {    input := []byte("## Hello, Markdown!

This is **bold text** and `code`.")    output := blackfriday.Run(input)    fmt.Println(string(output))}

The result is HTML code with an h2 heading, a paragraph, and strong/code tags. Blackfriday supports extensions: tables, strikethrough, task lists, and autolinks. To activate them, use:

html := blackfriday.Run(input,    blackfriday.WithNoExtensions(),    blackfriday.WithExtensions(blackfriday.CommonExtensions),)

3. The goldmark library (recommended)

Goldmark is a modern Markdown parser written in pure Go. It fully complies with the CommonMark 0.30 specification and provides a flexible API for extensions. Installation:

go get github.com/yuin/goldmark

Basic example:

package main

import (    "bytes"    "fmt"    "github.com/yuin/goldmark")

func main() {    source := []byte("# Heading

Regular text with **bold** and *italic*.")    var buf bytes.Buffer    if err := goldmark.Convert(source, &buf); err != nil {        panic(err)    }    fmt.Println(buf.String())}

Goldmark is easily extensible. Built-in extensions include tables, task lists, footnotes, autolinks, and code highlighting via chroma. Example with the table extension:

import (    "github.com/yuin/goldmark"    "github.com/yuin/goldmark/extension")

markdown := goldmark.New(    goldmark.WithExtensions(extension.Table),)

4. Code highlighting with chroma

Chroma is a syntax highlighting library for Go that supports over 190 programming languages and many themes. Installation:

go get github.com/alecthomas/chroma/v2

Integration with goldmark looks like this:

package main

import (    "bytes"    "fmt"    "github.com/alecthomas/chroma/v2/quick"    "github.com/yuin/goldmark"    highlighting "github.com/yuin/goldmark-highlighting/v2")

func main() {    source := []byte("```gopackage main

import \\"fmt\\"

func main() {    fmt.Println(\\"Hello, world!\\")}```")    markdown := goldmark.New(        goldmark.WithExtensions(            highlighting.Highlighting,