Three sheets: your HTML, your brand, your file.

Look at the brand mark. It is three sheets, stacked and tilted. The red sheet is your HTML, the thing you already made. The blue sheet is your brand, the logo, colours, and fonts that make it yours. The ink sheet is your file, the finished PDF or image you send out. thirds.ai is the step that turns the first two into the third.

We started because that step was too slow. A person with a good invoice, report, or ad still had to open a design tool, paste the new numbers, check the spacing, and export a file by hand. When the data changed, they did it all again. We wanted the design made once and every file after that made by a button, an API call, or an AI agent.

So thirds.ai keeps one editable template for each design. You can build it from a few words in the AI chat, from HTML you paste in, or from a source image we rebuild for you. Then you fill it with data as often as you need, in the web app, through the API, or through MCP from your own agent.

Every PDF and image comes out of a real Chromium browser. Your CSS, web fonts, grid, and flexbox work the way they do on the web, because it is the web. We pin the browser version and record it with each file, so a render you made last month still looks the same today, as long as the fonts and pictures it loads from the web have not changed.

Each template version is saved for good. When you render with the latest version, we write down which exact version that was. Old renders never change under you.

We treat your content with care. Your prompts, HTML, images, and data are yours. We do not train AI on your content. When the AI chat needs a model, we send your content to the AI provider only under the terms we disclose in our privacy policy, and nowhere else.

The renderer runs with hard limits on time, memory, and pages, and it only loads assets from public web addresses. That keeps one bad page from slowing down everyone else.

One finished PDF, PNG, JPEG, or WebP costs one credit. A failed render costs nothing, and you can try again. Hand edits and the live preview in the editor are free, so you can take your time before you export.

The AI chat is the one place credits go faster. The first build of a template costs 50 credits, and each later chat message costs 10, because a real model does real work each time. The price is on the button before you press it.

You press a button to spend a credit. A page load or a plain link never spends one. The free plan gives you 25 credits every month with no card, and paid plans start at $29 a month. Every finished file stays for 30 days so you can download it when you are ready.