ooxml.dev is an interactive reference for ECMA-376 (Office Open XML) — the standard behind .docx, .xlsx, and .pptx files. Built by the SuperDoc team, who implemented a native OOXML renderer from scratch. Features: live previews (edit XML, see it render in real-time using SuperDoc's native OOXML engine), implementation notes (documents real-world behavior where Microsoft Word diverges from the spec), semantic spec search (18,000+ spec chunks searchable by meaning via MCP server at api.ooxml.dev/mcp), and practical guides for paragraphs, tables, borders, bidirectional text, and document creation. The OOXML spec is 5,000+ pages of PDFs with no rendering guidance — this site bridges that gap with knowledge from people who actually implemented the spec. Covers WordprocessingML (the .docx subset). SuperDoc is open source at superdoc.dev. Built by Caio Pizzol (caiopizzol.com), Head of DX at SuperDoc.

Search the ECMA-376 spec with AI

Connect your MCP-compatible client to search 18,000+ specification chunks using natural language queries.

Available Tools

search_ecma_spec — Semantic search across the specification.
get_section — Retrieve a specific section by ID.
list_parts — Browse the specification structure.

What is MCP?

The Model Context Protocol (MCP) is an open standard that lets AI assistants connect to external data sources and tools.