Rust

HTML to PDF in Rust

One POST, a PDF back. No headless browser to install, no Chromium to keep patched, no fonts to install on the box — the render happens on a warm browser that is already running.

Render HTML to a PDF

use serde_json::json;
use std::{env, fs, time::Duration};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = reqwest::Client::builder()
        .timeout(Duration::from_secs(60))
        .build()?;

    let response = client
        .post("https://api.pdfcraft.dev/v1/render")
        .bearer_auth(env::var("PDFCRAFT_API_KEY")?)
        .json(&json!({
            "html": "<h1>Invoice 1042</h1>",
            "options": { "printBackground": true }
        }))
        .send()
        .await?
        .error_for_status()?;

    fs::write("invoice.pdf", response.bytes().await?)?;
    Ok(())
}

Read a PDF back as JSON

The same key works for extraction. Send a PDF, name the fields you want by the label printed on the page, and get them back with the raw text, a coerced value, a confidence and a bounding box.

use base64::{engine::general_purpose::STANDARD, Engine};

let encoded = STANDARD.encode(fs::read("statement.pdf")?);

let body: serde_json::Value = client
    .post("https://api.pdfcraft.dev/v1/extract")
    .bearer_auth(env::var("PDFCRAFT_API_KEY")?)
    .json(&json!({
        "file": encoded,
        "schema": { "account_number": "string", "closing_balance": "currency" }
    }))
    .send()
    .await?
    .json()
    .await?;

println!("{}", body["fields"]["closing_balance"]["value"]);

What bites in Rust

`.error_for_status()?` before reading the body, or a 429 gets written to disk as a PDF containing JSON.
`response.bytes()`, not `.text()` — `.text()` is lossy UTF-8 decoding and will mangle the file.
reqwest has no default timeout. Build the client with one rather than relying on the connection to fail.

Errors are one shape

Every failure is {"error":{"code","message","docs_url"}} with a stable code, so you can switch on error.code rather than parsing prose. The two worth handling explicitly are rate_limited — honour Retry-After — and render_failed, which means your HTML broke rather than ours did.

The same thing in another language

Or try it with no code at all in the playground. A free key is 100 renders a month.