# H2M
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[![Docs.rs][docs-badge]][docs-url]
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[![Rust][rust-badge]][rust-url]
[crates-badge]: https://img.shields.io/crates/v/h2m.svg
[crates-url]: https://crates.io/crates/h2m
[docs-badge]: https://img.shields.io/docsrs/h2m.svg
[docs-url]: https://docs.rs/h2m
[ci-badge]: https://github.com/qntx-labs/h2m/actions/workflows/rust.yml/badge.svg
[ci-url]: https://github.com/qntx-labs/h2m/actions/workflows/rust.yml
[license-badge]: https://img.shields.io/badge/license-MIT%2FApache--2.0-blue.svg
[license-url]: LICENSE-MIT
[rust-badge]: https://img.shields.io/badge/rust-edition%202024-orange.svg
[rust-url]: https://doc.rust-lang.org/edition-guide/
**Fast, extensible HTML-to-Markdown converter for Rust — CommonMark + GFM, plugin architecture, zero `unsafe`.**
H2M converts HTML into clean Markdown with full CommonMark compliance and GitHub Flavored Markdown extensions. It uses a plugin-based rule system, supports reference-style links, relative URL resolution, and ships with an async CLI powered by `tokio` for high-concurrency batch scraping.
<p align="center">
<img src="demo.gif" alt="H2M CLI Demo"/>
</p>
## Quick Start
### Install the CLI
**Shell** (macOS / Linux):
```sh
**PowerShell** (Windows):
```powershell
Or via Cargo:
```bash
cargo install h2m-cli
```
### CLI Usage
```bash
h2m https://example.com
h2m page.html
Content extraction:
```bash
h2m -r https://blog.example.com/post # smart readable
h2m -s article https://blog.example.com/post # CSS selector
h2m -s '#content' https://example.com # by ID
```
JSON output (for agents / programmatic use):
```bash
h2m --json https://example.com # pretty JSON
h2m --json --extract-links https://example.com # with links
h2m --json url1 url2 url3 # NDJSON streaming
h2m --json --urls urls.txt -j 8 --delay 100 # batch + concurrency
```
Formatting:
```bash
h2m --gfm https://example.com # tables, strikethrough, task lists
h2m --link-style referenced page.html # reference-style links
h2m --heading-style setext page.html # === / --- underlines
h2m --user-agent "MyBot/1.0" https://example.com
h2m -o output.md https://example.com
```
### JSON Output
Single URL produces a pretty-printed JSON object:
```json
{
"markdown": "# Example Domain\n\n...",
"metadata": {
"title": "Example Domain",
"description": "This domain is for use in illustrative examples.",
"language": "en",
"ogImage": "https://example.com/og.png",
"sourceUrl": "https://example.com",
"url": "https://example.com/",
"statusCode": 200,
"contentType": "text/html; charset=UTF-8",
"elapsedMs": 234
},
"links": ["https://example.com/about"]
}
```
`sourceUrl` is the original request; `url` is the final URL after redirects. `links` only appears with `--extract-links`.
Multiple URLs produce NDJSON (one JSON object per line), ideal for streaming pipelines.
### Library Usage
```rust
// One-liner with CommonMark defaults
let md = h2m::convert("<h1>Hello</h1><p>World</p>");
assert_eq!(md, "# Hello\n\nWorld");
```
```rust
// Full control with builder
use h2m::{Converter, Options};
use h2m::plugins::Gfm;
use h2m::rules::CommonMark;
let converter = Converter::builder()
.options(Options::default())
.use_plugin(&CommonMark)
.use_plugin(&Gfm)
.domain("example.com")
.build();
let md = converter.convert(r#"<a href="/about">About</a>"#);
assert_eq!(md, "[About](https://example.com/about)");
```
### Async Scraping
Enable the `scrape` feature for async HTTP scraping with built-in concurrency control, rate limiting, and streaming output:
```rust,no_run
use h2m::scrape::Scraper;
let scraper = Scraper::builder()
.concurrency(8)
.gfm(true)
.extract_links(true)
.build()?;
// Single scrape
let result = scraper.scrape("https://example.com").await?;
println!("{}", result.markdown);
// Batch with streaming callback
let urls = vec!["https://a.com".into(), "https://b.com".into()];
Ok(r) => println!("{}", r.markdown),
Err(e) => eprintln!("error: {e}"),
}
}).await;
```
## Design
- **CommonMark + GFM** — full spec compliance with tables, strikethrough, task lists, reference-style links
- **Plugin architecture** — extend with custom rules via the `Rule` trait
- **Async batch pipeline** — `tokio` + `reqwest`, semaphore concurrency, streaming NDJSON (`scrape` feature)
- **JSON output** — nested camelCase metadata (title, description, language, ogImage, sourceUrl/url, statusCode, contentType, elapsedMs) for agent/programmatic consumption
- **Smart readable extraction** — two-phase content detection: semantic selectors → noise stripping (`nav`, `footer`, `aside`, `header`, ARIA roles)
- **Smart scraping** — configurable User-Agent, HTTP 3xx + HTML meta-refresh redirect following (including `<noscript>`-wrapped)
- **Zero-copy fast paths** — `Cow<str>` escaping, zero `unsafe`, `Send + Sync`
## Conversion Examples
**Input HTML:**
```html
<h1>Title</h1>
<p>A <strong>bold</strong> and <em>italic</em> paragraph with <a href="https://example.com">a link</a>.</p>
<ul>
<li>First item</li>
<li>Second item</li>
</ul>
<pre><code class="language-rust">fn main() {}</code></pre>
```
**Output Markdown:**
```markdown
# Title
A **bold** and *italic* paragraph with [a link](https://example.com).
- First item
- Second item
```rust
fn main() {}
```
```
## Supported HTML Elements
### CommonMark (built-in)
| `<h1>`-`<h6>` | `# Heading` (ATX) or underline (Setext) |
| `<p>`, `<div>`, `<section>`, `<article>` | Block paragraph |
| `<strong>`, `<b>` | `**bold**` |
| `<em>`, `<i>` | `*italic*` |
| `<code>`, `<kbd>`, `<samp>`, `<tt>` | `` `inline code` `` |
| `<pre><code>` | Fenced code block with language detection |
| `<a href="...">` | `[text](url)` or reference-style |
| `<img src="..." alt="...">` | `` |
| `<ul>`, `<ol>`, `<li>` | Bullet/numbered lists with nesting |
| `<blockquote>` | `> quoted text` |
| `<hr>` | `---` |
| `<br>` | Hard line break |
| `<iframe>` | `[iframe](url)` |
### GFM Extensions (with `--gfm`)
| `<table>` | GFM pipe table with alignment |
| `<del>`, `<s>`, `<strike>` | `~~strikethrough~~` |
| `<input type="checkbox">` | `[x]` or `[ ]` (task list) |
### Auto-removed
| `<script>` | Removed (content stripped) |
| `<style>` | Removed (content stripped) |
| `<noscript>` | Removed (content stripped) |
## Custom Rules
Extend the converter with your own rules by implementing the `Rule` trait:
```rust
use h2m::{Converter, Rule, Action, Context};
use h2m::rules::CommonMark;
use scraper::ElementRef;
#[derive(Debug)]
struct HighlightRule;
impl Rule for HighlightRule {
fn tags(&self) -> &'static [&'static str] { &["mark"] }
fn apply(&self, content: &str, _el: &ElementRef<'_>, _ctx: &mut Context<'_>) -> Action {
Action::Replace(format!("=={content}=="))
}
}
let mut builder = Converter::builder()
.use_plugin(CommonMark);
builder.add_rule(HighlightRule);
let converter = builder.build();
let md = converter.convert("<p>This is <mark>important</mark></p>");
assert!(md.contains("==important=="));
```
## License
Licensed under either of:
- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or <https://www.apache.org/licenses/LICENSE-2.0>)
- MIT License ([LICENSE-MIT](LICENSE-MIT) or <https://opensource.org/licenses/MIT>)
at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project shall be dual-licensed as above, without any additional terms or conditions.
---
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