OPF vs other presentation formats

Open alternatives to PPTX

Two open file formats cover two different jobs. For files that people edit in office software, the open standard is ODP (OpenDocument Presentation), an OASIS standard published as ISO/IEC 26300. LibreOffice Impress uses it natively, and PowerPoint can open and save it.

For decks that software and language models write, OPF is an open, MIT-licensed JSON format with a JSON Schema: a program or agent writes one JSON document, validates it, keeps it in git, and converts it to PPTX or PDF when people need a file. OPF is an open standard with a public spec, but it isn't ratified by ISO or OASIS. PPTX itself also has a published specification (ECMA-376, ISO/IEC 29500), but it is a zipped XML bundle that is hard to diff, review or generate.

At a glance

These tools solve different problems. PPTX is the universal exchange format for office software, and ODP, an ISO standard, is its open counterpart. Marp, Slidev, and reveal.js are excellent authoring tools for humans who write Markdown or HTML. OPF is an interchange format for software: structured JSON with a schema, built so programs and language models can produce, validate, and transform decks. The comparison below is about format properties, not tool quality.

PPTX / OOXML

PPTX is the most compatible presentation format in existence, and the right output target when decks must open in PowerPoint. As a source format it is hard to work with: a .pptx file is a zip archive of interlinked XML parts, so version control sees opaque binary changes, code review is impossible, and LLMs cannot reliably emit it. A common pipeline is to author or generate decks as OPF JSON, validate them, and convert to PPTX at the end.

ODP / OpenDocument

ODP is the presentation part of the OpenDocument Format, an OASIS standard published as ISO/IEC 26300. It is the right choice when an organization needs office files in a vendor-neutral, standardized format. As a source format it shares the PPTX trade-offs: a .odp file is a zip archive of XML parts, so diffs, code review and reliable generation by a model are hard. OPF does not replace it for office editing; it covers the earlier step, where software writes and checks the deck.

Google Slides API

The Slides API is a capable way to drive Google Slides programmatically, but the deck lives in Google's cloud rather than in your repository. There is no portable document you can check in, diff, or validate offline, and the API's request/response types are not a document schema. If your decks must live in Google Workspace, it is the right tool; if you want decks as reviewable source files, it isn't designed for that.

Marp & Slidev

Marp and Slidev are first-class tools for developers who write slides. Markdown source is diffable and pleasant to author, and both render beautifully. The trade-off is structure: Markdown has no schema, so a generated deck can't be validated before rendering, and slide semantics (audience, narrative beats, layout intent, chart data) live in loosely defined front matter or comments. For human-authored talks they are a great choice; for machine pipelines the lack of a contract shows quickly.

OPF also has its own Markdown dialect, converted both ways by opf convert, for people and agents who would rather write text. It is a way to author the same deck, not a second format: the Markdown converts to OPF JSON, which is validated, and OPF JSON converts back to Markdown without loss. See Markdown authoring.

A deck can also be written as YAML (*.opf.yaml, also converted by opf convert): the same JSON document without braces and quoted keys, with comments. It parses to exactly the OPF JSON and round-trips. See YAML authoring.

reveal.js

reveal.js is a mature HTML presentation framework with a rich plugin ecosystem. Like the Markdown tools, the source is diffable, but it is presentation code rather than presentation data: content, styling, and behavior mix in free-form HTML. Generating it with an LLM works for simple decks but there is no way to validate the output, and extracting structured content back out is hard.

When to use OPF

OPF is the right choice when decks are produced or consumed by software:

• LLMs or agents generate decks via structured output and you need to validate before rendering.
• Decks live in git and changes go through code review like any other source file.
• You are building a renderer, converter, or analyzer and want a stable, open document contract.
• One source document must target multiple outputs (PowerPoint, SVG, images).

If a human just wants to write a talk, Marp and Slidev are mature choices, and OPF Markdown is there when the deck should also be a validated, convertible document. OPF is the wrong choice when decks must be edited collaboratively in office software, where PPTX or Google Slides remain the destination. Start with the developer docs or the format spec.

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