Codex bundles a headless LibreOffice to build Office files locally
Simon Willison found ~430MB of headless LibreOffice inside the ChatGPT app — the engine behind Codex's Office edits. Plus ChatGPT Health wires in Epic EHRs.
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What's inside the 1.7GB runtime
On first launch the ChatGPT desktop app pulls a ~1.7GB codex-primary-runtime folder, and ~430MB of it is a headless LibreOffice (LibreOfficeDev.app on macOS). Bundled alongside: Python, Node.js, Poppler for PDFs, and Git.
Why your agent ships an office suite now
Those binaries are what Codex reaches for when it reads or edits Word, Excel, and PowerPoint files — headless soffice converts between .docx/.xlsx/.pptx and even legacy .xls, all locally with no cloud round-trip. If you script document workflows, the muscle already shipped.
The catch: bloat, licensing, attack surface
It's ~430MB you may never touch, and commenters flagged possible MPL-2.0 attribution gaps in OpenAI's open-source notices plus the security surface of shipping a full office suite. macOS gets the LibreOffice build; Windows caches a leaner set (git, poppler, libheif, PowerShell).
Elsewhere: ChatGPT Health plugs into Epic
OpenAI wired ChatGPT Health into Epic's EHR (read-only across ~325M patient records) and shipped a Healthcare Public Data plugin exposing PubMed, ClinicalTrials.gov, RxNorm, DailyMed, and CMS Coverage. With a BAA, builders can run Codex and connectors in compliant health workflows.