Where PPTX came from
PPTX is Microsoft PowerPoint. It belongs to the presentation family, which webp.now handles by rendering the document exactly as it would print and encoding each page as an image.
The technical picture
Compression: Zipped XML or binary container. Transparency: Not applicable. Animation: Not applicable. Colour: Document colour. Typical file size relative to WebP: varies with page count and embedded media.
Where it opens
Microsoft PowerPoint and compatible office suites. This is usually the deciding factor when choosing between PPTX and WebP — WebP renders in every browser but is uneven in desktop software, while PPTX has a very different support profile.
Converting PPTX to WebP
Each slide is rendered at its full layout and saved as a WebP image — ideal for embedding a deck in a web page, a blog post or a docs site where nobody should need PowerPoint to read it. Animations, transitions, speaker notes and hyperlinks do not survive rasterisation. Keep the deck for presenting.
Converting WebP to PPTX
Convert WebP to PPTX when the destination requires it. Expect the PPTX output to be varies with page count and embedded media — that difference is the price of getting a format the destination will actually accept.