pdfs.build is a PDF template engine with a REST API. Design a document template once, then generate PDFs from it by passing JSON data. Every template pairs its layout with a JSON schema, so payloads are validated before anything renders and a bad request fails as a clear error instead of a quietly broken document. Documents are compiled by Typst, an open source typesetting engine, rather than a headless browser. That is what makes renders fast and deterministic, and it is why a template designed against three line items still paginates correctly at ninety. Repeating table headers, totals blocks that never split across a page break, and footers that hold their position are part of the layout language rather than hints you hope a browser honours. Templates can be designed by chatting with an AI editor, imported from a Word document you already have, or built by your own AI agent through the MCP server. An embeddable React editor lets your customers edit their own templates inside your product, white label, with per-tenant billing attribution. Used for invoices, quotations, reports, certificates, contracts, and any other document generated from application data. Free tier includes 2 templates and 50 renders per month.