OpenMontage is an open-source (AGPLv3) agentic video production system that turns an AI coding assistant into a complete video studio. You describe what you want in plain language and the agent handles the full pipeline — research, scripting, asset generation, editing and final composition — across a documented set of 12 pipelines, 52 tools and 500+ agent skills. Beyond image-based videos, it can assemble real footage for free and open workflows: the agent builds a corpus from free stock footage and open archives, then retrieves and edits clips to match the script. It is provider-agnostic, running on top of coding assistants and the model providers you already use, and is developed in the open with its build documented publicly.