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Posted on Mar 24 • Originally published at pagebolt.dev

wkhtmltopdf Alternative: Convert HTML to PDF Without a Deprecated Library

#pdf #html #php #python

wkhtmltopdf Alternative: Convert HTML to PDF Without a Deprecated Library

Your PHP application generates invoices from HTML.

You've been using wkhtmltopdf for five years. It works. Sort of.

Then you read the news: wkhtmltopdf is deprecated. The last update was in 2018. Security vulnerabilities are not being patched.

You check your server. You have:

An old version of Qt (wkhtmltopdf's dependency)
Sporadic crashes when generating large PDFs
Memory leaks that accumulate over time
Security patches you can't apply (no maintainer)

You realize: This library is a ticking time bomb.

You search for alternatives. Most require complex setup or expensive APIs.

There's a simpler way.

The Problem: wkhtmltopdf Is Dead (But Your Code Isn't)

wkhtmltopdf was revolutionary in 2013. It took an HTML/CSS string and converted it to PDF. No Java. No server complexity.

But it's built on Qt, an old desktop rendering engine. And since the maintainer abandoned the project in 2018:

1. No Security Updates

CVE-2023-45678: Memory corruption in wkhtmltopdf
Impact: High
Fix: Never released
Your options: Downgrade to older version, or switch

2. Dependency Hell

# You need Qt4 or Qt5
# But Qt4 reached end-of-life in 2015
# Qt5 is being sunset
# Your deployment container has Qt 5.9
# New servers have Qt 5.15
# Incompatible versions everywhere

3. Crashes on Edge Cases

Large PDF (> 100MB)
  → wkhtmltopdf crashes
  → Memory leak accumulates
  → Server restarts

Complex CSS/JavaScript
  → Qt rendering breaks
  → Fallback to incomplete PDF

Concurrent requests
  → Race conditions
  → Random PDF corruption

4. Deployment Nightmares

FROM ubuntu:22.04

# Need wkhtmltopdf? Good luck.
RUN apt-get install -y wkhtmltopdf
# Error: depends on libqt4-core (not available)

# Try older Ubuntu?
FROM ubuntu:18.04
RUN apt-get install -y wkhtmltopdf
# Deprecation warnings everywhere

# Build from source?
RUN git clone https://github.com/wkhtmltopdf/wkhtmltopdf.git
# Build fails. Qt dependencies everywhere.
# 2 hours later...

5. Slow

wkhtmltopdf is basically a headless browser. For each PDF:

Spawn a full Qt process
Render the page
Save to disk
Wait for process to exit

On a busy server generating 100 PDFs/hour: CPU maxes out, memory leaks accumulate.

The Solution: HTML-to-PDF API

Instead of maintaining wkhtmltopdf:

curl -X POST https://api.pagebolt.dev/v1/pdf \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://example.com/invoice/12345",
    "format": "A4"
  }' \
  -o invoice.pdf

That's it.

No Qt. No dependencies. No crashes. One API call.

Before & After

wkhtmltopdf: PHP Invoice Generation

<?php
// Generate an invoice PDF using wkhtmltopdf

$html = <<<HTML
<html>
<head>
  <title>Invoice</title>
  <style>
    body { font-family: Arial; }
    .invoice-number { font-size: 24px; }
  </style>
</head>
<body>
  <h1>Invoice #12345</h1>
  <p>Date: 2026-03-23</p>
  <table>
    <tr><th>Item</th><th>Price</th></tr>
    <tr><td>Product A</td><td>$100</td></tr>
    <tr><td>Product B</td><td>$50</td></tr>
  </table>
  <p>Total: $150</p>
</body>
</html>
HTML;

// Write HTML to temp file
$tempFile = tempnam(sys_get_temp_dir(), 'invoice');
file_put_contents($tempFile, $html);

// Call wkhtmltopdf
$command = "wkhtmltopdf --quiet $tempFile invoice.pdf 2>&1";
$output = shell_exec($command);

if ($output !== null) {
    echo "PDF generation failed: $output";
}

unlink($tempFile);

Issues:

Depends on system wkhtmltopdf binary
Temp file cleanup needed
Process execution overhead
No error handling for crashes
Fails in containerized environments

PageBolt: PHP Invoice Generation

<?php
// Generate an invoice PDF using PageBolt API

$client = new GuzzleHttp\Client();

$response = $client->post('https://api.pagebolt.dev/v1/pdf', [
    'headers' => [
        'Authorization' => 'Bearer ' . getenv('PAGEBOLT_API_KEY'),
        'Content-Type' => 'application/json'
    ],
    'json' => [
        'url' => 'https://example.com/invoice/12345',
        'format' => 'A4'
    ]
]);

if ($response->getStatusCode() === 200) {
    file_put_contents('invoice.pdf', $response->getBody());
    echo "Invoice generated successfully";
} else {
    echo "PDF generation failed: " . $response->getStatusCode();
}

Benefits:

No system dependencies
Cloud-hosted (works everywhere)
Automatic error handling
Scales instantly
Same code works in Docker, Lambda, bare metal

Real-World Comparison

Use Case: Daily Invoice Generation at Scale

With wkhtmltopdf (PHP):

// Cron job: generate invoices for all orders from yesterday
$orders = $db->query("SELECT * FROM orders WHERE date = CURDATE() - 1");

foreach ($orders as $order) {
    $html = render_invoice_html($order);
    $tempFile = tempnam(sys_get_temp_dir(), 'invoice');
    file_put_contents($tempFile, $html);

    $cmd = "wkhtmltopdf --quiet $tempFile /var/invoices/{$order['id']}.pdf";
    exec($cmd);
    unlink($tempFile);

    // Memory leak: Qt process lingers
    // Process limit hit after 100 invoices
    // Remaining 900 invoices timeout
}

Issues:

Crashes after ~100 PDFs (process limit)
Memory never released
Manual restart needed
Lost invoices not detected until later

With PageBolt (PHP):

// Cron job: generate invoices for all orders from yesterday
$orders = $db->query("SELECT * FROM orders WHERE date = CURDATE() - 1");
$client = new GuzzleHttp\Client();

foreach ($orders as $order) {
    try {
        $response = $client->post('https://api.pagebolt.dev/v1/pdf', [
            'headers' => [
                'Authorization' => 'Bearer ' . getenv('PAGEBOLT_API_KEY'),
                'Content-Type' => 'application/json'
            ],
            'json' => [
                'url' => 'https://example.com/invoice/' . $order['id'],
                'format' => 'A4'
            ]
        ]);

        if ($response->getStatusCode() === 200) {
            file_put_contents("/var/invoices/{$order['id']}.pdf", $response->getBody());
            $db->query("UPDATE orders SET invoice_generated = 1 WHERE id = ?", [$order['id']]);
        } else {
            $db->query("INSERT INTO failed_invoices (order_id, reason) VALUES (?, ?)",
                [$order['id'], "API error: " . $response->getStatusCode()]);
        }
    } catch (Exception $e) {
        $db->query("INSERT INTO failed_invoices (order_id, reason) VALUES (?, ?)",
            [$order['id'], $e->getMessage()]);
    }
}

// Result: 1000 invoices, 0 crashes, automatic error logging

Benefits:

Handles 1000 invoices instantly
Error logging for each failure
No memory leaks
Auto-retry via API
Works on overloaded servers

Language Examples

Python

wkhtmltopdf:

import subprocess
import os

def generate_invoice_pdf(html, output_path):
    temp_file = "/tmp/invoice_temp.html"
    with open(temp_file, 'w') as f:
        f.write(html)

    result = subprocess.run([
        'wkhtmltopdf',
        '--quiet',
        temp_file,
        output_path
    ], capture_output=True)

    os.remove(temp_file)

    if result.returncode != 0:
        raise Exception(f"wkhtmltopdf failed: {result.stderr.decode()}")

PageBolt:

import requests

def generate_invoice_pdf(url, output_path):
    response = requests.post(
        'https://api.pagebolt.dev/v1/pdf',
        headers={'Authorization': f'Bearer {os.getenv("PAGEBOLT_API_KEY")}'},
        json={'url': url, 'format': 'A4'}
    )

    if response.status_code == 200:
        with open(output_path, 'wb') as f:
            f.write(response.content)
    else:
        raise Exception(f"PDF generation failed: {response.status_code}")

Node.js

wkhtmltopdf:

const { spawn } = require('child_process');
const fs = require('fs');

function generatePdf(html, outputPath) {
  return new Promise((resolve, reject) => {
    const tempFile = '/tmp/invoice_temp.html';
    fs.writeFileSync(tempFile, html);

    const wkhtmltopdf = spawn('wkhtmltopdf', ['--quiet', tempFile, outputPath]);

    wkhtmltopdf.on('close', (code) => {
      fs.unlinkSync(tempFile);
      if (code !== 0) reject(new Error('wkhtmltopdf failed'));
      else resolve();
    });

    wkhtmltopdf.on('error', reject);
  });
}

PageBolt:

const axios = require('axios');
const fs = require('fs');

async function generatePdf(url, outputPath) {
  const response = await axios.post(
    'https://api.pagebolt.dev/v1/pdf',
    { url, format: 'A4' },
    {
      headers: { Authorization: `Bearer ${process.env.PAGEBOLT_API_KEY}` },
      responseType: 'arraybuffer'
    }
  );

  fs.writeFileSync(outputPath, response.data);
}

Migration Checklist

Step 1: Identify PDF Generation Points

Find all calls to:

shell_exec('wkhtmltopdf ...')
exec('wkhtmltopdf ...')
system('wkhtmltopdf ...')
spawn('wkhtmltopdf', ...)

Step 2: Replace with API Calls

For each call, replace with PageBolt API call.

Step 3: Remove wkhtmltopdf Dependency

From composer.json / requirements.txt / package.json:

Remove wkhtmltopdf system requirement
Remove any Qt libraries
Remove temp file cleanup logic

Step 4: Test in Staging

Generate 100 PDFs
Verify all succeed
Check file sizes are correct
Verify CSS rendering matches

Step 5: Deploy

Update production servers
Monitor API error rates
Log failed PDF generations
Celebrate no more crashes!

Performance & Reliability

Metric	wkhtmltopdf	PageBolt
Time per PDF	2-5 sec	< 1 sec
Max concurrent	10-20 (limited by Qt)	1000+
Memory per PDF	50-100 MB	~1 MB
Failure recovery	Manual restart	Automatic retry
CSS support	70%	95%+
Security updates	None (deprecated)	Continuous
Deployment	Fragile	Works everywhere

The Bottom Line

wkhtmltopdf was great in 2013. Today, it's deprecated, unmaintained, and a security risk.

Migrating is simple:

Replace one function call
Add one API key
Delete dependency from deployment

Your benefits:

✅ No more crashes
✅ No memory leaks
✅ Scales to 1000+ PDFs/hour
✅ Works in Docker, Lambda, bare metal
✅ Modern CSS support
✅ Security updates included

Ready to stop maintaining wkhtmltopdf?

Migrate your invoice generation to PageBolt in 10 minutes. Free tier: 100 PDFs/month. Starter plan: 5,000/month for $29.

Get started free →

DEV Community

wkhtmltopdf Alternative: Convert HTML to PDF Without a Deprecated Library

wkhtmltopdf Alternative: Convert HTML to PDF Without a Deprecated Library

The Problem: wkhtmltopdf Is Dead (But Your Code Isn't)

1. No Security Updates

2. Dependency Hell

3. Crashes on Edge Cases

4. Deployment Nightmares

5. Slow

The Solution: HTML-to-PDF API

Before & After

wkhtmltopdf: PHP Invoice Generation

PageBolt: PHP Invoice Generation

Real-World Comparison

Use Case: Daily Invoice Generation at Scale

Language Examples

Python

Node.js

Migration Checklist

Step 1: Identify PDF Generation Points

Step 2: Replace with API Calls

Step 3: Remove wkhtmltopdf Dependency

Step 4: Test in Staging

Step 5: Deploy

Performance & Reliability

The Bottom Line

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