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Comparison · Repeat PDFs from editable templates and JSON

thirds.ai vs PDFMonkey

Both tools make PDFs and images from a saved design and your new details. PDFMonkey has a visual Builder and code templates in HTML, CSS, and Liquid (vendor claim). thirds.ai designs are HTML too, and your code can also send plain HTML without saving a design.

Make a sample invoiceSee the plans

We aren't connected to PDFMonkey. PDFMonkey is a trademark of its owner. We checked PDFMonkey's features and prices on 12 September 2026. Facts and numbers about PDFMonkey come from PDFMonkey. Where we say which tool fits, or that we didn't find a feature, that's our opinion.

1 credit
makes 1 PDF or image
50 credits
free every month, no card
$29
a month for Starter, with 2,500 credits
4 formats
PDF, PNG, JPEG, and WebP

Try it yourself

Test the same job in both tools

Make a real long document in both tools. Check page breaks, fonts, pictures loaded from the web, and how you download the file. Check how long the finished file has to stay available, and whether you need passwords or form fields. If your template is a Word or Excel file instead of HTML, compare Carbone instead.

Make a sample invoice
An A4 invoice with a deep-teal block cut on a diagonal, Fold & Meridian top-left, a huge cream total, a tilted coral disc holding the invoice number, then a cream section with a billed-to block, a four-column line-item table, a coral total, and a payment box.
Design studio invoice

Feature by feature

Side by side

What you needthirds.aiPDFMonkey
InputsDescribe it to the AI, paste your own HTML, or upload a picture that becomes a design you can edit. Your code can also send plain HTML without saving a design.A saved visual Builder or code template plus a JSON object. Code templates use HTML, CSS or SCSS, and Liquid v4 (vendor claim). A minimal saved template can pass pre-built HTML from the payload, but PDFMonkey has no raw HTML endpoint (vendor claim).
OutputsPDF, PNG, JPEG, and WebP.PDF, PNG, JPG, and WebP (vendor claim).
Template editingA visual editor and an AI chat work on the same HTML design. Saved versions never change.A visual Builder and a code editor for HTML, Liquid, CSS or SCSS, test data, headers, footers, and print settings (vendor claim).
Document controlsPage sizes, margins, headers, footers, backgrounds, and scale.Headers, footers, paper formats, margins, fillable PDF forms, and password protection (vendor claim).
Brand and AI pathsBrand kits hold your logo, colours, and fonts. AI can draft or change a design, and it can rebuild a picture as a design in your brand.Full HTML and CSS let customers apply their own brand (vendor claim). We found no brand-kit, AI template-chat, source-image reconstruction, or MCP offer in the pages we checked (our reading).
API and deliveryREST endpoints for templates, PDFs, and images, plus MCP. Jobs can return later through signed webhooks and expiring downloads.REST endpoints create documents from a template and payload. Async calls support polling or signed Svix webhooks; a sync endpoint waits for the result (vendor claim).
Workflow toolsWeb app, REST API, and MCP.Zapier, Make, n8n, Workato, Bubble, Glide, Ruby, and Node.js paths are documented (vendor claim).
Entry paid planStarter is $29 a month for 2,500 credits. One credit makes one PDF or image.Starter is €5 a month for 300 documents, one-day retention, and a 30-second generation limit (vendor price and limits). External resources are included (vendor claim).
Free use50 free credits a month for a verified account. Making a design with AI or from a picture costs 50 credits, and free credits don't pay for it.The Free plan includes 20 documents each month, one-day retention, and a 30-second generation limit (vendor limits). It blocks external images, fonts, CSS, and JavaScript (vendor claim). A new account also gets a 30-day Pro trial with 300 documents and no card (vendor claim).
Where it fitsTeams that want HTML they can edit, their brand saved once, and one place to make both PDFs and images.Teams that want a hosted PDF template product with Liquid, form and password controls, and no-code connections (our reading).

Read before you decide

Limits on both sides

thirds.ai limits

  • A PDF can have up to 100 pages. The pictures and fonts it loads can total 20 MiB, and the finished file can be 25 MiB.
  • An image can be up to 32 megapixels and 25 MiB.
  • It doesn't provide fillable PDF form fields.
  • It doesn't give a file a permanent public link. Download links expire, so you store the files you need to keep.
  • It doesn't have ready Zapier, Make, n8n, Workato, Bubble, or Glide integrations.

PDFMonkey limits we found

  • The Free plan cannot load external images, fonts, CSS, or JavaScript (vendor claim).
  • Free and Starter keep a generated document for one day; Pro keeps it for seven days (vendor limits). Pro+ and Premium offer unlimited retention (vendor claim).
  • The Free and Starter generation limit is 30 seconds; Pro is two minutes, Pro+ is three minutes, and Premium is five minutes (vendor limits).
  • PDFMonkey needs a saved template even when a customer sends complete HTML in the payload (vendor claim). Its documented pattern uses a minimal wrapper template.
  • Monthly document quotas do not roll over (vendor claim). Boost Pack credits expire at the end of the current billing cycle (vendor claim).
  • We found no published page-count or output-size limit in the plan and generation pages we checked (our reading). Test a representative long file and ask PDFMonkey about any limit that matters to your job.

Pricing

How we compared prices

  • We checked prices and plan limits on 12 September 2026. Check the PDFMonkey pricing page and our pricing page before you buy.
  • PDFMonkey Starter is €5 a month for 300 documents (vendor price and quota). Pro is €15 a month for 3,000 documents (vendor price and quota). Taxes are extra (vendor claim).
  • PDFMonkey sells 1,000-document Boost Packs for €5 on paid plans (vendor price and quantity). The credits expire at the next subscription renewal and are not refundable (vendor claim).
  • One thirds.ai credit makes one PDF of up to 100 pages, or one image. The AI uses credits too. It costs 50 to build a new design or rebuild one from a picture, and 25 for a later AI edit. A file that fails costs nothing.
  • The two tools price in different currencies and keep files for different times. Compare the plans that cover the files you make each month, the outside pictures and fonts you load, how long files stay, and team access.

Switching

Moving from PDFMonkey

Start with one published PDFMonkey template and one real payload. Save the current HTML, CSS, Liquid, print settings, input JSON, and finished PDF. Move the layout to thirds.ai HTML, then change Liquid output and control tags to the supported MiniJinja form. Keep the same field names where they are clear.

Map document_template_id to template_id, payload to data, and PDFMonkey's pending status to a thirds.ai render request. Replace PDFMonkey's download_url handling with the thirds.ai job status and signed download. If you use webhooks, map success and failure events and verify the thirds.ai signature before you accept the result.

PDF form fields, password protection, and permanent share links do not have direct thirds.ai replacements. Keep PDFMonkey for a document that needs them, or change that requirement before you move it. Compare the saved reference file with the new result before the next document type moves.

Checked and dated

Sources

Keep comparing

Try the same job here

Open the Design studio invoice template and make a sample PDF. A developer can then follow Use templates with your data to make the next customer's PDF from code.

Change the details and make a real file for free. It has a watermark. Sign in to keep working on the same design with the same details.

Make a sample invoiceSee the plans