Transactional – HTML + Tailwind to PDF via API

TL;DR

TL;DR: Transactional lets you design PDF templates in HTML and Tailwind CSS, then render them on-demand through a simple API call — no layout engine to manage.

Source and Accuracy Notes

⚠️ This section is MANDATORY. All links must be verified from actual source, not guessed.

• Project page: transactional.dev ← visited and verified
• Source repository (open-source version): github.com/yves1da2vinci3/designMyPdf-frontend ← README read
• License: MIT (verified via GitHub API)
• HN launch thread: news.ycombinator.com/item?id=40498173

What Is Transactional?

Transactional is a PDF generation API that flips the typical approach. Instead of building PDFs programmatically with a library like jsPDF or wkhtmltopdf, you design the document visually using HTML, Tailwind CSS, and Handlebars templates — then call an API endpoint to render it.

The product targets backend developers and SaaS builders who need to generate transactional PDFs: invoices, receipts, contracts, reports. The core pitch: your frontend developer designs the template, your backend just POSTs variables and gets back a hosted PDF URL.

The rendering pipeline:

1. Design the template using HTML + Tailwind in the visual editor
2. Mark transactional variables with Handlebars syntax ({{name}}, {{amount}})
3. POST the document ID and variables to /v1/generate
4. Receive a ready-to-serve PDF URL from the CDN

The open-source version, Design My PDF, mirrors this workflow using Next.js, Mantine, and jsPDF for client-side rendering.

Setup Workflow

Step 1: Create a Template

Sign up at transactional.dev and create a new document. The editor lets you lay out a PDF page using standard HTML elements and Tailwind utility classes.

<div class="p-8 bg-white">
  <h1 class="text-2xl font-bold text-gray-900">Invoice</h1>
  <p class="mt-2">&#123;&#123;customer_name&#125;&#125;</p>
  <p class="text-xl font-semibold">$&#123;&#123;amount&#125;&#125;</p>
</div>

Handlebars supports conditionals and loops:

{{#each items}}
  <tr>
    <td>&#123;&#123;name&#125;&#125;</td>
    <td>$&#123;&#123;price&#125;&#125;</td>
  </tr>
&#123;&#123;/each&#125;&#125;

Step 2: Call the API

curl -X POST https://api.transactional.dev/v1/generate \
  -H "Content-Type: application/json" \
  -d '{
    "document_id": "invoice-v3",
    "variables": {
      "customer_name": "Acme Corp",
      "amount": "249.00",
      "items": [
        {"name": "Pro Plan", "price": "199.00"},
        {"name": "Setup", "price": "50.00"}
      ]
    }
  }'

Response:

{
  "pdf_url": "https://cdn.transactional.dev/pdf/8c7a3f2..."
}

Step 3: Serve or Store the PDF

The generated PDF is hosted on their CDN and returned in the API response. You can embed it in an email, serve it to a user, or pipe it through your own storage.

Using the Open-Source Version

The Design My PDF repository is a full working implementation:

git clone https://github.com/yves1da2vinci3/designMyPdf-frontend.git
cd designMyPdf-frontend
yarn install

Set up environment variables (see .env.local template in the README):

NEXT_PUBLIC_API_URL=your_backend_url
CLOUDINARY_CLOUD_NAME=your_cloud_name
CLOUDINARY_API_KEY=your_key
CLOUDINARY_API_SECRET=your_secret

yarn dev

The open-source version runs entirely client-side using jsPDF, so there is no server-side rendering — the PDF generation happens in the browser. For production server-side generation, the hosted Transactional API is the intended path.

Deeper Analysis

What makes it different from alternatives?

The dominant pattern for PDF generation in web apps is using a server-side library (puppeteer, wkhtmltopdf, weasyprint) that renders a full HTML page to PDF. This works but requires running a headless browser or custom rendering stack. Transactional moves the design burden to a visual editor and exposes a single REST endpoint — the rendering complexity stays on their infrastructure.

Contrast with tools like:

• PDFKit (Ruby/Node) — programmatic PDF construction, no visual editor
• Decktape — converts HTML presentations to PDF, not transactional documents
• Re原型 — form builder to PDF, focused on static forms rather than API-driven generation

MCP support: Transactional exposes an MCP (Model Context Protocol) interface so AI agents can interact with the PDF generation workflow directly — create documents, render them, and embed the resulting URLs without human intervention. The MCP docs are at transactional.dev/docs/mcp.

Paper sizes: The editor supports A1 through A6 in both portrait and landscape orientations, with live preview in an iframe that simulates the actual paper size.

Practical Evaluation Checklist

• Sign up at transactional.dev and create a free account
• Design one template using the visual editor (invoice or receipt is a good start)
• Mark 3–5 Handlebars variables in the template
• Make a test POST call to /v1/generate with sample variables
• Verify the returned PDF URL loads correctly
• If using the open-source version: clone the repo, configure .env.local, run yarn dev, and test the client-side PDF export

Security Notes

• PDF templates run on Transactional’s infrastructure — verify their data handling policy before sending sensitive customer data through the API
• The open-source version processes PDFs client-side only; no data leaves the browser when using jsPDF directly
• Handlebars variable injection is server-side on the hosted product — sanitize variable content if it includes user-submitted strings

FAQ

Q: Does Transactional support custom fonts? A: The visual editor supports Tailwind’s default font stack. Custom font embedding in PDFs depends on whether the font is available in the PDF rendering pipeline — check the docs for the current font policy.

Q: Is there a free tier? A: The product offers a free starting tier. Specific limits (number of PDFs per month, storage) are available on the pricing page at transactional.dev.

Q: Can I self-host the full pipeline? A: The open-source Design My PDF repo covers the frontend/editor. The full API infrastructure (rendering engine, CDN hosting) is the hosted product and is not currently available as a self-hosted option.

Q: What happens to the generated PDF URLs? A: PDFs are hosted on Transactional’s CDN. The URL returned by the API is a direct link to the file. Check the service’s retention policy if you need long-term storage — you may want to download and re-upload to your own storage.

Q: How does MCP support work? A: The MCP interface lets AI agents create, edit, and render documents programmatically. This is useful for automated workflows where an AI agent needs to produce a PDF without human design steps.

Conclusion

Transactional solves the PDF generation problem from the design side rather than the code side. If your team already has a designer comfortable with HTML and Tailwind, it removes the back-and-forth between design and engineering that typically makes PDF-heavy features painful. The API-first model also makes it straightforward to integrate into any backend stack. The open-source version is useful for experimentation and smaller projects where client-side PDF generation is acceptable.