Why Use Rust for a Markdown-to-HTML Converter?

Rust is well-known for its performance, safety, and powerful tooling ecosystem. When it comes to building a Markdown-to-HTML converter, Rust allows you to process large files quickly, handle errors safely, and build cross-platform command-line tools with ease. You also benefit from excellent community crates like pulldown-cmark, which provides a fast, CommonMark-compliant Markdown parser in pure Rust.

Prerequisites

• Rust installed (https://rustup.rs)
• Basic knowledge of Rust syntax and the command line
• A text editor or IDE (like VS Code with rust-analyzer)
• Terminal access for running the project and CLI

Step 1: Create a New Rust Project

In your terminal, create a new project named md2html:

cargo new md2html
cd md2html

This sets up the base structure with Cargo.toml and src/main.rs.

Step 2: Add Dependencies

Edit Cargo.toml and add the following under [dependencies]:

[dependencies]
pulldown-cmark = "0.9"
clap = { version = "4.0", features = ["derive"] }

This brings in the Markdown parser and a command-line argument parser to handle user input easily.

Step 3: Write the Converter Logic

Open src/main.rs and replace its contents with this:

use std::fs;
use std::path::PathBuf;
use clap::Parser;
use pulldown_cmark::{Parser as MdParser, html::push_html};

#[derive(Parser)]
#[command(author, version, about)]
struct Args {
    /// Path to the input Markdown file
    input: PathBuf,

    /// Path to the output HTML file
    output: PathBuf,
}

fn main() {
    let args = Args::parse();

    let markdown = fs::read_to_string(&args.input)
        .expect("Failed to read input file");

    let parser = MdParser::new(&markdown);
    let mut html_output = String::new();
    push_html(&mut html_output, parser);

    fs::write(&args.output, html_output)
        .expect("Failed to write HTML output");

    println!("Converted {} to {}", args.input.display(), args.output.display());
}

This reads a Markdown file, parses it to HTML using pulldown-cmark, and saves the output to a file specified by the user via CLI arguments.

Step 4: Run the Converter

Create a sample Markdown file named example.md:

# Hello World

This is a **Markdown** file converted to HTML using Rust.

Then build and run your CLI tool:

cargo run -- example.md output.html

This will generate output.html with the converted HTML content from the Markdown source.

Step 5: Optional Improvements

• Add file existence checks and better error handling
• Support directories and batch conversion
• Embed CSS styles in the generated HTML
• Support both .md and .markdown extensions

Conclusion

You’ve built a fast and efficient Markdown-to-HTML converter in Rust using modern libraries. Along the way, you learned how to work with file I/O, external crates, command-line interfaces, and Markdown parsing — all within a single practical project.