ODT, HWP, PSD and other formats nobody documents

There is no list, and that is the real answer

Articles that hand you a definitive table of forty supported extensions have invented it. OpenAI has published four families and no extensions, so anything more specific is somebody's testing presented as documentation.

Which means the useful skill is working it out yourself, and there is a reliable test.

The ten second test

Open the file in a plain text editor. Notepad, TextEdit in plain mode, VS Code, anything.

You see readable words, possibly surrounded by markup and tags. The text is extractable, and ChatGPT will very likely handle it. RTF, HTML, XML, CSV and every code format look like this.

You see binary noise, rows of unreadable characters. There is no plain text to extract, and it needs converting first. PSD, DWG, most images and every archive look like this.

Format by format

ODT and ODS, the OpenDocument formats. Documents and spreadsheets in common use. Generally work. If one gives trouble, export to DOCX or plain text.

HWP, the Korean word processor format. A document, but not in common international use. Export to PDF or DOCX first.

PSD, Photoshop. A layered image, not a document. Any text in it is inside image layers, which are discarded on every plan except Enterprise. Export the text, or flatten to PNG and upload as an image.

DWG and DXF, CAD drawings. Not documents. Export to PDF, or take an image of the drawing, though be aware fine detail suffers.

EPUB, ebooks. Essentially structured HTML in a container, so it often works. Converting to plain text is more reliable and strips the packaging.

Pages, Numbers, Keynote, Apple's formats. Export to their Microsoft or PDF equivalents. Apple's native formats are packages rather than single files.

WPD, WordPerfect. Old enough to be worth converting without trying.

When it will not work, convert

Almost always the fastest path, and rarely lossy in any way that matters.

1. Open it in the software that made it

   Or LibreOffice, which opens an unusually wide range of formats for free.

2. Export to PDF, DOCX or plain text

   Plain text for content. PDF when layout matters. DOCX as a middle ground.

3. Upload the converted file

   Now it is an ordinary document with ordinary limits.

What converting costs you

Formatting, layout and images. Since images are discarded on every plan except Enterprise anyway, the real loss is presentation, and ChatGPT was working from the words regardless.

If your document's meaning genuinely lives in its layout, a floor plan, a design mockup, a complex form, then exporting to an image and uploading that as an image is the better route. Images are supported and capped at 20 MB each.