Show the Working

PPSX to HTML

Your presentation never leaves your browser, and nothing is downloaded to make this work. An OpenDocument file is a ZIP of XML and your browser can already unzip; the rest is reading.

…or drop one anywhere on this page.

One web page, one section per slide.

A complete document you can open anywhere, with each slide as its own section and a stylesheet that works in dark mode. It is a reading version of the talk rather than a copy of it: a slide is boxes at coordinates and a page reflows, so what is carried is the words and their structure.

The order of the slides is not the order of the files

This is the one thing about PowerPoint's format that will ruin a converter silently. The slides are ppt/slides/slide1.xml, slide2.xml and so on, and sorting those names is the obvious thing to do. Sorted as text they come out:

slide1, slide10, slide11, slide12, slide2, slide3…

So a twelve-slide deck arrives with slides ten, eleven and twelve sitting between the first and the second. Nothing errors. Nothing is missing. It is simply in the wrong order — and a deck of nine slides or fewer never shows it, so the fault survives every small test anybody writes.

The real running order is in ppt/presentation.xml, as a list of relationship ids resolved through ppt/_rels/presentation.xml.rels. That is where this page reads it from, and it was checked on a twelve-slide deck for exactly the reason above.

And the speaker notes are numbered separately

ppt/notesSlides/notesSlide1.xml is not the notes for slide one. It is the notes for whichever slide happens to be the first one that has any. A three-slide deck with notes on the third slide only contains exactly one notes file, numbered 1 — so a converter matching numbers puts the presenter's private remarks on the wrong slide entirely.

Each slide's own relationships say which notes file is its own, and that is the only thing that works. They are read separately, counted, and left out unless you ask for them.

A notes page also carries a picture of the slide and the slide NUMBER alongside the notes. Take every piece of text in it and the notes come out with a stray digit on the end; only the notes body is read.

A slideshow is the presentation, with a different label

A .ppsx and a .pptx are the same package. The only difference is a content type that tells PowerPoint to start presenting immediately rather than open the editor. Everything this page reads is identical.

What does not come across

The layout. A slide is boxes at coordinates; this is a document that reads top to bottom, so two columns become one after the other. Backgrounds, master slides, transitions and animations have nowhere to go. Pictures, charts, tables and embedded objects are counted but not carried, because they are separate parts inside the package.

Slide numbers, dates and footers are dropped on purpose: they are marked as furniture in the file, and a stale page number in the middle of a transcript helps nobody. Fields are dropped for the same reason — the number in one is whatever it was when the file was last saved.

Macros are never read and never run. A .pptm is a .pptx with a macro project inside it, and that project is exactly what cannot be turned into a document. If your file has one it is said on screen, because “this had macros and they are gone” is worth knowing.

Where to go next