APITemplate.io Alternative: HTML to PDF API Compared

What APITemplate.io Gets Right

Any fair comparison starts with the strengths, because they are real. If these are the things you care about most, APITemplate.io may well be the better fit, and you should stay.

• The visual editor and template gallery. The drag-and-drop editor with a live side-by-side preview is one of the best in this space, and the gallery of ready-made invoice, certificate, and social-image templates gets a non-developer productive in minutes.
• Image generation as a first-class API. Banners, social cards, and QR images from templates with per-object overrides. Most PDF APIs do not offer this at all.
• Regional endpoints. Four regions (US, EU, Singapore, Australia) with in-region processing. If you have data-residency requirements, this matters.
• Async generation with webhooks. Fire a batch, get notified when each document is done. The webhook flow is well documented.
• SDK coverage. Official libraries for Python, JavaScript, PHP, C#, Java, and UIPath, plus polished Zapier, Make.com, n8n, Airtable, and Bubble integrations.

None of that is in dispute. The question is whether the pricing model and the template workflow fit how developers actually ship documents.

Where Power Users Hit the Ceiling

Here is the pattern behind most searches for an APITemplate.io alternative. None of these are deal-breakers alone. Together, they push high-volume and code-first teams to shop around.

1. Credit-based pricing, and images share the pool

The free plan is 50 PDFs or images per month. On the combined plans, every image you generate eats a credit that a PDF could have used, so a workflow that makes one PDF and one social image per order burns credits twice as fast as you budgeted. Plans step up in fixed tiers, so a spiky webhook-driven workload gets sized for its peak month, not its average.

2. Template caps, and templates live in their console

Free allows 3 templates, PDF Basic 20, PDF Standard 180. More important than the number is where templates live: in APITemplate.io's web console, referenced by a template_id. That means no version control, no code review on a template change, and no spinning up a variant per customer without touching the dashboard. With CustomJS the HTML template is a string in your request body, so it lives in your repo next to the code that fills it.

3. No documented way to wait for async JavaScript

APITemplate.io does support custom CSS and JavaScript in PDF templates, which is more than many competitors. But if your script fetches data, draws a Chart.js canvas, or renders a QR code asynchronously, there is no documented signal to tell the renderer "wait, I am not done yet". CustomJS has exactly that: set window.__RENDER_DONE__ = true when your async work finishes and the capture waits for it.

4. Two-step delivery

The REST API returns a JSON body with a download_url pointing at S3, so most integrations make two round trips per document: create, then fetch. There is a direct file mode, but it is capped at 4 to 6 MB depending on region. CustomJS returns the PDF bytes in the same synchronous call.

Pricing: APITemplate.io vs CustomJS

APITemplate.io meters monthly credits per plan; CustomJS meters requests per day. The comparison below uses APITemplate.io's annual-billing prices (monthly billing runs roughly 20 to 30 percent higher) and approximates CustomJS daily limits as monthly volume.

What it costs at three real volumes

APITemplate.io figures from apitemplate.io/pricing, checked August 23, 2026, annual billing. APITemplate.io meters monthly credits; CustomJS meters a daily request limit, so the monthly CustomJS figures are approximate and a very spiky load must still fit the daily cap. Always confirm current numbers on each provider's pricing page.

The honest read: if you specifically want managed image templates with a visual editor, APITemplate.io's combined plans buy you something CustomJS does not replicate one-to-one. For pure HTML to PDF volume, CustomJS is cheaper at every tier and dramatically cheaper at the top, and the 600-PDF free tier covers what many small automations need forever.

Feature Comparison

Try the Migration Live

Below is an APITemplate.io-style delivery note rebuilt as a CustomJS Nunjucks template. The left panel is the HTML template, the right is the JSON data you would have POSTed to APITemplate.io's create endpoint. Edit either side and render the PDF in your browser. This is the same engine that powers the production API.

The variables you see, like {{ delivery_number }} and the {% for item in items %} loop, are Nunjucks. If you have written a Jinja2 template for APITemplate.io, this is the same syntax family, on purpose.

Migrating Your Template: Jinja2 to Nunjucks

This is the easiest template migration in the PDF API space, because Nunjucks was explicitly modeled on Jinja2. Output tags, loops, conditionals, loop.index, whitespace control, and most filters are identical. What changes is Python-flavored details: method calls become filters, and printf-style formatting becomes arithmetic or a filter.

APITemplate.io (Jinja2)

<h1>Delivery Note {{ delivery_number }}</h1>
<p>Ship to: {{ customer.name.upper() }}</p>

<table>
  {% for item in items %}
    <tr>
      <td>{{ loop.index }}</td>
      <td>{{ item.sku }}</td>
      <td>{{ item.name }}</td>
      <td>{{ "%.2f"|format(item.qty * item.unit_weight) }} kg</td>
    </tr>
  {% endfor %}
</table>

{% if notes|length > 0 %}
  <p class="notes">{{ notes }}</p>
{% endif %}

CustomJS (Nunjucks)

<h1>Delivery Note {{ delivery_number }}</h1>
<p>Ship to: {{ customer.name | upper }}</p>

<table>
  {% for item in items %}
    <tr>
      <td>{{ loop.index }}</td>
      <td>{{ item.sku }}</td>
      <td>{{ item.name }}</td>
      <td>{{ (item.qty * item.unit_weight) | round(2) }} kg</td>
    </tr>
  {% endfor %}
</table>

{% if notes | length > 0 %}
  <p class="notes">{{ notes }}</p>
{% endif %}

The handful of things to know when you port a template:

The structural change is bigger than the syntax change: instead of editing a template in APITemplate.io's console and referencing its ID, you send the HTML with each request. Store it as a file in your codebase, load it, and pass it as input.html. For full template capabilities, see the HTML to PDF API reference, and for a general grounding in the conversion pipeline, the HTML to PDF conversion guide.

The curl Migration in One Look

APITemplate.io's create call returns JSON with a download_url on S3, so you typically make a second request to fetch the file. CustomJS is a single synchronous call that returns the PDF bytes.

Before: APITemplate.io

curl -X POST 'https://rest.apitemplate.io/v2/create-pdf?template_id=YOUR_TEMPLATE_ID' \
  -H 'X-API-KEY: YOUR_APITEMPLATE_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
    "delivery_number": "DN-2026-0815",
    "customer": { "name": "Northwind Trading GmbH" },
    "items": [ { "sku": "CJ-100", "name": "Widget", "qty": 4, "unit_weight": 1.2 } ]
  }'
# response: { "download_url": "https://...s3.amazonaws.com/...", "status": "success" }
# then fetch download_url to get the actual PDF

After: CustomJS

curl -X POST 'https://e.customjs.io/html2pdf' \
  -H 'x-api-key: YOUR_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
    "input": {
      "html": "<h1>Delivery Note {{ delivery_number }}</h1><p>Ship to: {{ customer.name }}</p>",
      "data": {
        "delivery_number": "DN-2026-0815",
        "customer": { "name": "Northwind Trading GmbH" }
      }
    }
  }' > delivery-note.pdf

One request, one PDF, no second fetch. The template moves from the query string's template_id into input.html, and your data payload stays almost byte-for-byte the same, just nested under input.data.

Migrating the Image API: Overrides to Screenshots

APITemplate.io's image API generates PNGs and JPEGs from stored image templates using per-object overrides. CustomJS approaches the same jobs differently: the screenshot endpoint at https://e.customjs.io/screenshot renders any HTML or live URL in the same headless Chromium and captures it as an image, on the same API key and the same quota as your PDFs.

In practice that means a social card or banner becomes a small HTML file with CSS instead of a console-managed image template. You lose the visual override editor, and you gain the full power of CSS layout, web fonts, and JavaScript in your images, plus one less credit pool to watch. If your image workflow is built around non-developers editing templates visually, this is the one migration step that changes how people work, so weigh it honestly.

Migrating a Make.com Scenario

If your Make.com scenario uses the APITemplate.io app, swapping it for CustomJS is a one-module change. The trigger, the field mapping, and the downstream steps (email, Google Drive, Slack) stay exactly the same.

Before (APITemplate.io app)

Trigger (Webhook / Sheets / Airtable)
   -> APITemplate.io: Create a PDF
        template: Delivery Note (template_id from console)
        data:     mapped fields
   -> HTTP: Get a file (fetch download_url)
   -> Email: send attachment

After (CustomJS module)

Trigger (Webhook / Sheets / Airtable)
   -> CustomJS: HTML to PDF
        html:  your Nunjucks template
        data:  mapped fields
   -> Email: send PDF output (no download step)

The scenario gets one module shorter: the extra HTTP step that fetched the S3 download URL disappears because CustomJS returns the file in the same call. Add the CustomJS module, paste your API key once as a connection, and map the same fields you already mapped into APITemplate.io's data payload. Full walkthrough in the Make.com integration guide and the HTML to PDF module docs.

Migrating an n8n Workflow

The n8n story is the same shape. Replace the APITemplate.io node with the CustomJS community node, or, if you prefer raw control, an HTTP Request node pointed at the endpoint.

Option A: HTTP Request node

{
  "method": "POST",
  "url": "https://e.customjs.io/html2pdf",
  "sendHeaders": true,
  "headerParameters": {
    "parameters": [
      { "name": "x-api-key", "value": "YOUR_API_KEY" }
    ]
  },
  "sendBody": true,
  "bodyParameters": {
    "parameters": [
      {
        "name": "input",
        "value": "={{ { html: $json.template, data: $json.order } }}"
      }
    ]
  },
  "options": { "response": { "response": { "responseFormat": "file" } } }
}

Option B: native CustomJS node

Install the community node, add your API key as a credential, and pick the HTML to PDF operation. Map your template and data fields, and the node returns the PDF as binary you can attach to an email or push to storage. See the n8n HTML to PDF node docs and the installation guide.

Using Zapier instead? CustomJS works there too via a Webhooks by Zapier POST step using the same payload as the curl example above, so an APITemplate.io-on-Zapier flow ports without restructuring.

The Thing APITemplate.io Does Not Document: Waiting for Async JavaScript

APITemplate.io deserves credit here: it does let you put custom JavaScript in a PDF template, which already beats most template-based competitors. The gap is asynchrony. Charts render on the next animation frame, QR libraries draw asynchronously, and fetch calls take however long they take. Without a way to tell the renderer "capture now", you are betting that your script finishes before the snapshot happens.

CustomJS makes that contract explicit. Because conversion happens in a full headless Chromium, any browser library runs at render time, and when your template does asynchronous work you set window.__RENDER_DONE__ = true once the content is ready. The renderer waits for that flag before capturing the page.

<canvas id="chart" width="600" height="240"></canvas>
<script src="https://cdn.jsdelivr.net/npm/chart.js"></script>
<script>
  const chart = new Chart(document.getElementById("chart"), {
    type: "bar",
    data: {
      labels: ["Jan", "Feb", "Mar"],
      datasets: [{ label: "Shipments", data: [120, 190, 160] }]
    },
    options: {
      animation: {
        // tell CustomJS the async render finished
        onComplete: () => { window.__RENDER_DONE__ = true; }
      }
    }
  });
</script>

We cover this pattern in depth in HTML to PDF with async JavaScript and generating QR codes in PDFs.

When You Should Stay on APITemplate.io

A migration guide that pretends the other tool is never the right choice is not worth reading. Stay on APITemplate.io if:

• Non-developers own your templates. The WYSIWYG editor with live preview and the ready-made gallery are real advantages if the person maintaining layouts does not want to touch HTML.
• Your image workflow is template-driven. Visually managed image templates with per-object overrides have no direct CustomJS equivalent. The screenshot endpoint covers the output, not the editing experience.
• You need in-region processing. If EU, Singapore, or Australia data residency is a hard requirement, APITemplate.io's regional endpoints are the safer answer today.
• You depend on webhook-driven async batches. If your architecture is built around fire-and-forget generation with webhook callbacks, budget time to restructure before switching to a synchronous API.

For everyone else, especially developers who want templates in version control, render-time JavaScript with an explicit done signal, and flat request-based pricing instead of shared credits, CustomJS is the leaner fit.

Conclusion

APITemplate.io is a polished product with the best visual editor and the broadest template gallery in its class. The reasons to look for an alternative are not about quality. They are about credit-based pricing that images and PDFs share, templates locked to a console ID, and the missing contract for asynchronous JavaScript at render time.

CustomJS keeps what matters for developers: Jinja2 templating becomes near-identical Nunjucks, the same Make.com and n8n workflows keep their field mappings, and the API collapses create-then-download into a single call. On top you get 600 free PDFs a month, full Chromium rendering with the __RENDER_DONE__ async signal, and one key that also covers screenshots and scraping. The migration is a filter-level template diff and a one-module swap, not a rebuild.

Evaluating more than one option? We wrote the same honest breakdown for PDFMonkey in our PDFMonkey alternative guide.

Start free with 600 PDFs per month