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Comparison · Repeat documents from Office or HTML templates

thirds.ai vs Carbone

Carbone takes a Word, Excel, or PowerPoint file as the template, fills it with your details, and turns it into a PDF. thirds.ai does the same job with an HTML to PDF design. You edit it in the browser or with AI, like this invoice template.

Make a sample invoiceSee the plans

We aren't connected to Carbone. Carbone is a trademark of its owner. We checked Carbone's features and prices on 17 September 2026. Where we say which tool fits, 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

Fill the same invoice in both tools. Use a DOCX or HTML invoice in Carbone and the matching HTML design in thirds.ai. Compare each PDF with what Word or Excel would make. Then decide if you need to host it yourself or can keep everything in HTML.

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.aiCarbone
InputsDescribe it to the AI, paste your own HTML, or upload a picture that becomes a design you can edit. Your code sends the HTML itself. It can't load a page URL.A DOCX, XLSX, PPTX, ODT, ODS, HTML, or custom XML file as the template, filled with your JSON data (vendor claim).
OutputsPDF, PNG, JPEG, and WebP.PDF, DOCX, XLSX, PPTX, ODS, HTML, XML, CSV, and Markdown, plus a separate Document Conversion API for other formats (vendor claim). No PNG, JPEG, or WebP output on the pages we read (our reading).
Render engineA fixed version of Chromium with print styles and PDF page settings.LibreOffice by default for PDF and format conversion, with OnlyOffice and Chromium listed as alternative converters (vendor claim). Office layout rules can carry over from the source file (our reading).
Template design and editingA visual editor and an AI chat work on the same design. Saved versions never change.Carbone Studio previews and versions a saved template, but you design the layout in Word, Excel, PowerPoint, or LibreOffice, not in a browser canvas (vendor claim). An open-source Carbone Skill helps AI coding tools draft the template markup (vendor claim).
Brand kitsSave your logo, colours, and fonts once, and your designs can use them.Not shown on the pages we read (our reading). Brand elements live inside the Office template file itself.
API and MCPA REST API at /v1/pdf, /v1/image, and /v1/templates, plus an MCP server for AI agents.A REST API at https://api.carbone.io with POST /template, POST /render/{templateId}, and GET /render/{renderId}, using a Bearer token, plus an official MCP server (vendor claim).
Self-hostingNot offered. We run the service and store your files for you.An open-source Community Edition you can self-host with Docker, plus a paid On-Premise licence starting around €1,500 a year for the Fit tier (vendor price, checked 17 September 2026).
Entry paid planStarter is $29 a month for 2,500 credits. One credit makes one PDF or image.Essential is €29 a month, or €26 a month billed annually, for 1,000 documents, 500 templates, and 2 parallel renders a month (vendor price and limits, checked 17 September 2026).
Free tier50 free credits a month for a verified account, no card. Making a design with AI or from a picture costs 50 credits, and free credits don't pay for it.The Cloud Free plan gives 100 documents and 100 templates a month, with 1 parallel render (vendor limits, checked 17 September 2026). The self-hosted Community Edition needs your own infrastructure instead of a document cap.
Where it fitsTeams with HTML designs who want a browser editor, an AI chat, a template gallery, and images as well as PDFs.Teams that already design reports, invoices, or contracts in Word, Excel, or PowerPoint and want that same file filled with data, or who need to self-host the renderer (our reading). Compare DocRaptor or PDFMonkey instead when your app already builds finished HTML.

Read before you decide

Limits on both sides

thirds.ai limits

  • It doesn't accept or produce DOCX, XLSX, PPTX, or ODT files. Every file is a PDF or an image made from HTML.
  • It doesn't load a page URL as the input. Your app sends the HTML text.
  • You can't host it yourself. We run it for you.
  • It doesn't edit Office files. Designs are HTML, and you edit them in the browser or with the AI chat.

Carbone limits we found

  • It does not show a brand-kit feature, a source-image import, or a template gallery on the pages we read (our reading).
  • Carbone Studio previews and versions a template; it is not a browser canvas editor for the layout itself (vendor claim).
  • A synchronous render call has a 60-second limit; a longer job needs a webhook and gets a five-minute limit (vendor claim).
  • PDF conversion needs LibreOffice installed; without it, Carbone can only return the template's original file format (vendor claim).

Pricing

How we compared prices

  • We checked pricing on 17 September 2026. Prices can change, so check the Carbone pricing page and our pricing page before you decide.
  • 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. See credits and billing.
  • One Carbone document is one render call with a JSON and image payload under 1 MB; a larger payload counts as more than one document (vendor claim).
  • Carbone prices in euros and thirds.ai prices in US dollars. Compare each plan with the number of files you really make each month.
  • The Carbone Cloud Free plan gives 100 documents a month, no card stated on the pricing page. The thirds.ai free plan gives 50 credits a month with the editor and library included. Free credits don't pay for AI, so an AI build needs trial credits, a credit pack, or a paid plan.

Switching

Moving from Carbone

Map the template and the fill call. Carbone stores a DOCX, XLSX, PPTX, ODT, or HTML file as a templateId and fills it by posting JSON to POST /render/{templateId} (vendor claim). thirds.ai stores an HTML template and fills it with a render request that returns a signed download when the job succeeds. If your source design lives in Word or Excel today, rebuild the layout in HTML, or start from a close gallery template and edit it in the visual editor.

The larger change is the render engine and the file format. Carbone converts an Office document with LibreOffice, so page breaks and fonts follow Office rules; thirds.ai renders HTML with Chromium, so the CSS a browser reads controls page breaks, headers, and footers. Follow the pattern in our wkhtmltopdf migration guide: save sample inputs and outputs, move one document type, compare the result, then move the next. Start with Create your first PDF. If your app already sends finished HTML instead of an Office file, our DocRaptor comparison and PDFMonkey comparison cover that same kind of switch.

Checked and dated

Sources

Keep comparing

Try the same job here

Open the Design studio invoice template and type in your own details. If you already have HTML, start with the PDF quickstart.

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