JavaScriptTutorial

HTML to PDF in Express (Node.js)

Generate PDFs from any Express route in a few lines of fetch.

01. Install

# Use built-in fetch (Node 18+) or install undici / node-fetch
# npm install dotenv  (if you don't already have it)
# Add to .env:
# PDFMYHTML_API_KEY=pmh_live_xxxxxxxxxxxxxxxxxxxx

02. Basic call

// routes/invoice.js
import express from 'express';

const router = express.Router();

router.get('/invoice/:id.pdf', async (req, res) => {
    const html = renderInvoiceHtml(req.params.id); // your template fn

    const apiRes = await fetch('https://api.pdfmyhtml.com/v1/html-to-pdf', {
        method: 'POST',
        headers: {
            'X-API-Key': process.env.PDFMYHTML_API_KEY,
            'Content-Type': 'application/json',
        },
        body: JSON.stringify({ html, wait: true }),
    });

    const { download_url } = await apiRes.json();
    const pdfBuffer = Buffer.from(await (await fetch(download_url)).arrayBuffer());

    res.set('Content-Type', 'application/pdf');
    res.send(pdfBuffer);
});

export default router;

03. Error handling

// Production-ready: timeout, status checks, error logging
import express from 'express';

const router = express.Router();

router.get('/invoice/:id.pdf', async (req, res) => {
    try {
        const apiRes = await fetch('https://api.pdfmyhtml.com/v1/html-to-pdf', {
            method: 'POST',
            headers: {
                'X-API-Key': process.env.PDFMYHTML_API_KEY,
                'Content-Type': 'application/json',
            },
            body: JSON.stringify({ html: renderInvoiceHtml(req.params.id), wait: true }),
            signal: AbortSignal.timeout(30_000),
        });

        if (!apiRes.ok) {
            console.error('pdfmyhtml HTTP', apiRes.status, await apiRes.text());
            return res.status(500).send('Could not generate PDF');
        }

        const data = await apiRes.json();
        if (data.status !== 'COMPLETED') {
            return res.status(503).send('PDF still processing — try async');
        }

        const pdfBuffer = Buffer.from(await (await fetch(data.download_url)).arrayBuffer());
        res.set('Content-Type', 'application/pdf');
        res.send(pdfBuffer);
    } catch (err) {
        console.error('pdfmyhtml error', err);
        res.status(500).send('PDF service unavailable');
    }
});

export default router;

04. Async pattern (high volume)

// Async pattern with BullMQ: enqueue → worker polls → write to S3
// Avoids holding the Express request open.

import { Queue, Worker } from 'bullmq';

const pdfQueue = new Queue('pdf', { connection: { host: 'redis' } });

// In your route:
router.post('/invoice/:id/pdf', async (req, res) => {
    const apiRes = await fetch('https://api.pdfmyhtml.com/v1/html-to-pdf', {
        method: 'POST',
        headers: {
            'X-API-Key': process.env.PDFMYHTML_API_KEY,
            'Content-Type': 'application/json',
        },
        body: JSON.stringify({ html: renderInvoiceHtml(req.params.id), wait: false }),
    });
    const { job_id } = await apiRes.json();

    await pdfQueue.add('poll', { invoiceId: req.params.id, jobId: job_id });
    res.json({ accepted: true, jobId: job_id });
});

// Worker:
new Worker('pdf', async (job) => {
    while (true) {
        await new Promise((r) => setTimeout(r, 2000));
        const r = await fetch(`https://api.pdfmyhtml.com/v1/jobs/${job.data.jobId}`, {
            headers: { 'X-API-Key': process.env.PDFMYHTML_API_KEY },
        });
        const data = await r.json();
        if (data.status === 'COMPLETED') {
            const pdf = await (await fetch(data.download_url)).arrayBuffer();
            // upload to S3, store reference, send email, etc.
            return;
        }
        if (data.status === 'FAILED') throw new Error(data.error_message);
    }
}, { connection: { host: 'redis' } });

05. Real-world example

// Stripe webhook → invoice PDF → email via Resend
import express from 'express';
import { Resend } from 'resend';
import Stripe from 'stripe';

const app = express();
const stripe = new Stripe(process.env.STRIPE_SECRET);
const resend = new Resend(process.env.RESEND_API_KEY);

app.post('/webhooks/stripe', express.raw({ type: 'application/json' }), async (req, res) => {
    const event = stripe.webhooks.constructEvent(
        req.body, req.headers['stripe-signature'], process.env.STRIPE_WEBHOOK_SECRET
    );

    if (event.type === 'invoice.paid') {
        const inv = event.data.object;
        const html = renderInvoiceHtml(inv);  // your Handlebars/EJS render

        const apiRes = await fetch('https://api.pdfmyhtml.com/v1/html-to-pdf', {
            method: 'POST',
            headers: {
                'X-API-Key': process.env.PDFMYHTML_API_KEY,
                'Content-Type': 'application/json',
            },
            body: JSON.stringify({ html, wait: true }),
        });
        const { download_url } = await apiRes.json();
        const pdf = await (await fetch(download_url)).arrayBuffer();

        await resend.emails.send({
            from: 'billing@yourapp.com',
            to: inv.customer_email,
            subject: `Invoice ${inv.number}`,
            html: 'Your invoice is attached.',
            attachments: [{ filename: `invoice-${inv.number}.pdf`, content: Buffer.from(pdf) }],
        });
    }

    res.json({ received: true });
});

Common gotchas

01.Node 18+ has built-in `fetch`. If you're still on Node 16, install `undici` or `node-fetch` and import explicitly — no top-level polyfill needed.
02.Don't set `Content-Length` manually when piping the PDF buffer — Express + Node's default streaming handles it correctly. Manual `Content-Length` will truncate large PDFs.
03.For high-volume use, the sync 25s wait pattern will exhaust your event loop under load. Use BullMQ / Inngest / Temporal to enqueue and process asynchronously.
04.`AbortSignal.timeout()` is Node 18+ only. On older runtimes use `AbortController` with `setTimeout` to clear it.

Going deeper? Read the full guide on cost trade-offs vs self-hosted Headless Chrome.